August 2010
Volume 51, Issue 8
Free
Biochemistry and Molecular Biology  |   August 2010
Variable Retinal Phenotypes Caused by Mutations in the X-Linked Photopigment Gene Array
Author Affiliations & Notes
  • Liliana Mizrahi-Meissonnier
    From the Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
  • Saul Merin
    From the Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
  • Eyal Banin
    From the Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
  • Dror Sharon
    From the Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
  • Corresponding author: Dror Sharon, Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel; dror.sharon1@gmail.com
  • Footnotes
    2  These authors contributed equally to the work presented here and should therefore be regarded as equivalent authors.
Investigative Ophthalmology & Visual Science August 2010, Vol.51, 3884-3892. doi:10.1167/iovs.09-4592
  • Views
  • PDF
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to Subscribers Only
      Sign In or Create an Account ×
    • Get Citation

      Liliana Mizrahi-Meissonnier, Saul Merin, Eyal Banin, Dror Sharon; Variable Retinal Phenotypes Caused by Mutations in the X-Linked Photopigment Gene Array. Invest. Ophthalmol. Vis. Sci. 2010;51(8):3884-3892. doi: 10.1167/iovs.09-4592.

      Download citation file:


      © 2017 Association for Research in Vision and Ophthalmology.

      ×
  • Supplements
Abstract

Purpose.: To examine the involvement of the long (L) and middle (M) wavelength-sensitive cone opsin genes in cone-dominated phenotypes.

Methods.: Clinical and molecular analyses included family history, color vision testing, full-field electroretinography (ERG), linkage analysis, and mutation detection.

Results.: Eighteen families were recruited that had X-linked retinal disease characterized by cone impairment in which affected males usually had nystagmus, reduced visual acuity, normal to subnormal rod ERG, and reduced or extinguished cone ERG responses. A search for mutations in the L-M pigment gene array revealed disease-causing mutations in six families. In two of them, novel mutations were identified: a large deletion affecting both opsin genes and a single L opsin gene harboring a likely pathogenic mutation, p.Val120Met. A third family carried a single hybrid gene with the p.Cys203Arg mutation. Patients from the three remaining families carried a single opsin gene harboring two similar rare haplotypes. Although the phenotype of members in one of the families was compatible with blue cone monochromacy (BCM), patients from the two other families, who shared an identical haplotype, had only reduced or even normal full-field cone ERGs, but maculopathy was evident.

Conclusions.: Novel and known mutations affecting the L-M opsin gene array were identified in families with X-linked cone-dominated phenotypes. The results show that different mutations in this gene array can cause a variety of phenotypes, including BCM, cone dystrophy, and maculopathy. Males with X-linked cone-dominated diseases should be routinely analyzed for mutations in the L-M opsin gene array.

Cone dystrophies (CDs) are a group of heterogeneous inherited retinal disorders characterized by bilateral impairment of visual acuity (VA), reduced or absent color vision, central visual field loss, photophobia, and reduced or absent cone electroretinogram (ERG) responses. The phenotype may be accompanied by high myopia and nystagmus. At early disease stages, it is difficult to distinguish between CD and other cone-dominated retinal phenotypes, such as achromatopsia and cone–rod degeneration. 1,2  
Two X-linked (XL) genes, RPGR and the cone opsin gene array, are known to cause XLCD. 38 The L and M opsin genes (long- and middle-wavelength sensitive opsin genes) reside in a head-to-tail tandem array on Xq28. A normal opsin gene array contains a locus control region (LCR), a single L gene, and at least one M gene, 9 each harboring six coding exons with a high degree of similarity (96%). Mutations in the XL-opsin gene array can lead to either a mild color vision deficiency (affecting approximately 8% of males) or the more severe phenotype blue-cone monochromacy (BCM), which is a rare congenital type of XLCD. Color vision deficiencies can be divided into three types: protanopia (a dichromacy in which the function of the L opsin is impaired or absent), deuteranopia (a dichromacy in which the function of the M opsin is impaired or absent), and anomalous trichromacy (mainly due to a shift in spectral sensitivity). If, however, both L and M opsins do not function, the patients have BCM (MIM: 303700; Mendelian Inheritance in Man; http://www.ncbi.nlm.nih.gov/Omim/ provided in the public domain by the National Center for Biotechnology Information, Bethesda, MD) mainly caused by large deletions that include the LCR region. 1,7,8,10 In addition, the presence of a single gene with an inactivating point mutation (mainly p.Cys203Arg) is also a common cause of BCM, 1,2,7,8,11,12 as are rare mutations, such as a single gene with an internal deletion 12,13 and a missense mutation present on all copies of opsin genes. 1,2,7,8,10,11 BCM and CD are closely related phenotypes but can be distinguished via the short S-cone ERG, which is well preserved in BCM. 1,2 Most patients with BCM were reported to have a stationary cone disorder, but a few also manifest macular atrophy over time and/or progressive visual loss. 8  
We report the first analysis of the XL opsin gene cluster in the Jewish population. Our cohort included 18 Jewish families of various origins with a diagnosis of XLCD or CRD phenotype. Six of the families were indeed found in this study to harbor mutations in the L-M opsin gene array, and all mutations are likely to cause dysfunction of both opsins. The affected individuals present highly variable retinal phenotypes associated with these mutations, ranging from severe BCM in one family carrying a large deletion, to mild maculopathy with reduced or even normal full-field cone function in families carrying a single opsin gene harboring missense mutations. 
Methods
Patient Recruitment
This study, which involved human patients, conformed to the tenets of the Declaration of Helsinki. Informed consent was obtained from the subjects after explanation of the nature and possible consequences of the study. The research was approved by the institutional review board (IRB). DNA was purified from blood samples (FlexiGene kit; Qiagen, Valencia, CA). 
Clinical Evaluation
A full ophthalmic examination including assessment of VA, ocular motility, pupillary reaction, biomicroscopic slit lamp, and dilated fundus examination was performed. Subsequently, full-field (ff)ERG and color vision testing (Ishihara 38-plate and the Farnsworth-Munsell D-15 tests) were performed according to the ability and cooperation of the patients, as previously described. 14 ffERGs were recorded with corneal electrodes and a computerized system (UTAS 3000; LKC, Gaithersburg, MD). In the dark-adapted state, a rod response to a dim blue flash (Wratten 47b; Eastman Kodak, Rochester, NY) and a mixed cone–rod response to a white flash (2.35 cd · s/m2) were acquired. Cone responses to 30-Hz flashes of white light (9.4 cd · s/m2) were acquired on a background of 21 cd/m2. All ERG responses were filtered at 0.3 to 500 Hz, and signal averaging was used. Color fundus photography and fluorescein angiography were performed (CF-60; Canon, Tokyo, Japan; or model FF450PLUS, Carl Zeiss Meditec, Dublin, CA fundus camera). Optical coherence tomography (OCT) was performed with the Stratus OCT3 system (Carl Zeiss Meditec) or the Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany). OCT data were compared with the normal values reported by Chan et al., 15 who found a mean (±SD) central foveal thickness of 212 ± 20 μm using the Stratus OCT3 system. 15 Since retinal thickness is measured differently by the Zeiss and Heidelberg systems, all results were normalized to conform with the Stratus OCT3 method of measurement. 
Screening for Mutations
Sequencing analysis of the LCR, promoters, and all six exons of the XL-opsin genes was performed by direct sequencing of PCR reactions that were either unique to a specific region (e.g., LCR, L promoter) or common to both the L and M opsin genes (e.g., exons 1–6). The oligonucleotide sequences had been reported previously as amplifying the LCR region, exon 4, exon 5, or L and M promoters, 1 or were designed by us (Supplementary Table S1). The distinction between the L and M genes was based on known amino acid differences located within exons 2 and 5. Analysis of the first and downstream genes in the opsin cluster was performed as previously described. 16,17  
Whole X-Chromosome Linkage Analysis
Twenty-eight microsatellite markers covering the whole X-chromosome were used to reconstruct the X-chromosome haplotype in family MOL0110. In addition, we used microsatellite markers (DXS1068, DXS8016, DXS8014, DXS8102, DXS8113, DXS556, and DXS998, DXS1123, D3S2390, DXY5154) that are specific to either the RP3 locus or Xq28. 
Results
We initially recruited a large Moroccan Jewish family (MOL0110) containing 33 affected males (Fig. 1, Table 1), 13 of whom were clinically examined and given a diagnosis of XLCD/CRD. The affected males, who appeared mainly in generations III and V, had various degrees of nystagmus, markedly impaired VA, normal to subnormal rod ERG responses, and severely reduced or extinguished ffERG cone responses (Table 2). Color vision was markedly abnormal: The affected males could not identify any of the Ishihara plates and made a large number of errors, with mixed protan and deutan defects, on the D-15 test. Fundus examination did not reveal pathologic findings in most of the patients, even at advanced ages, and fluorescein angiography (FA) was essentially normal (Figs. 2A–C). However, some thinning of the macular region was evident on OCT scans, even in young patients (Figs. 2D–F). Linkage analysis using 28 microsatellite markers covering the whole X-chromosome identified a segregating region on Xq28, including the L and M cone opsin gene array. We subsequently screened the opsin gene array for mutations and identified a large novel deletion containing most of the L opsin gene and about half of the M opsin gene. A detailed analysis of the deletion boundaries, performed with different sets of primers, revealed a 46,217-bp deletion (c.9_OPN1MW:578+271del46217; Fig. 3A). The mutant allele perfectly cosegregated in MOL0110 (Fig. 1). The proximal boundary was found within exon 1 of the L opsin gene (seven nucleotides downstream the initiation codon), and the distal boundary was found within intron 3 of the M opsin gene. This large deletion creates an abnormal hybrid opsin gene containing the LCR, the L opsin promoter region, and the beginning of exon 1 (including only the first 8 nucleotides of the open reading frame), followed by the 3′ region of the M opsin gene starting from intron 3 (Fig. 3A, Table 1). Based on the genetic findings, the diagnosis of affected males in family MOL0110 was revised to BCM rather than CD or CRD. 
Figure 1.
 
Families with mutations in the X-linked cone opsin gene array. Numbers above the family tree indicate family serial number, numbers within symbols indicate number of siblings, numbers below symbols indicate generation and individual numbers, arrows indicate index cases, and a dot within a circle designates an obligate carrier. M1 to M6 designate mutations identified in each family: M1, L3/M4 LIAVA; M2, L opsin LIAVA with a normal M opsin gene; M3, L opsin LIAVA; M4, L opsin p.Val120Met; M5, L3/M4 p.Cys203Arg; and M6, c.9_OPN1MW:578+271del46217.
Figure 1.
 
Families with mutations in the X-linked cone opsin gene array. Numbers above the family tree indicate family serial number, numbers within symbols indicate number of siblings, numbers below symbols indicate generation and individual numbers, arrows indicate index cases, and a dot within a circle designates an obligate carrier. M1 to M6 designate mutations identified in each family: M1, L3/M4 LIAVA; M2, L opsin LIAVA with a normal M opsin gene; M3, L opsin LIAVA; M4, L opsin p.Val120Met; M5, L3/M4 p.Cys203Arg; and M6, c.9_OPN1MW:578+271del46217.
Table 1.
 
Families with Identified Mutations In the L-M Cone Opsin Gene Array
Table 1.
 
Families with Identified Mutations In the L-M Cone Opsin Gene Array
Family Genes Opsin Gene Sequence* Mutation
Exon 2 Exon 3 Exon 4 Exon 5
65 111 116 120 153 171 174 178 180 203 230 233 236 274 275 277 279 285 298 309
L-wt† T I S V L/M V/I A/V I/V S/A C I/T A/S M/V I F Y V T A Y
% 67 89 93 96 56 97 97 88
M-wt† I/T V Y V M/L V A/V I/V A/S C T S V V L F F A P F
% 98 90 71 71 96
MOL0057 L3/M4 T I S V L I A V A C T S V V L F F A P F L3/M4 gene with the LIAVA haplotype
MOL0110 No intact gene NA NA C T S V V L F F A P F c.9_OPN1MW:578+ 271del46217
MOL0250 L T I S V L I A V S C I A M I F Y V T A Y L gene with the LIAVS haplotype
MOL0267 L T I S V L I A V S C I A M I F Y V T A Y L gene with the LIAVS haplotype
MOL0283 L T I S M L V V I S C I A M I F Y V T A Y c.358G>A (p.Val120Met)
MOL0432 L3/M4 T I S V L V A I A R T S V V L F F A P F c.706C>T (p.Cys203Arg)
MOL0152 L+M T/I I/V S/Y V L/M I/V A/V V/V A/A C I/T A/S M/V I/V F/L Y/F V/F T/A P Y/F L gene with the LIAVA haplotype‡
Table 2.
 
Clinical Data of Affected Males and Female Carriers with Mutations in the L and M Cone Opsin Array
Table 2.
 
Clinical Data of Affected Males and Female Carriers with Mutations in the L and M Cone Opsin Array
Patient Age Sex Refraction* Visual Acuity ffERG Protocol† FFERG Rod (μV)† ffERG Mixed Cone-Rod (μV)† ffERG Cone† Color Vision§
Amp (μV) IT (mS)
Affected Males
MOL0110 III:2 44 −18.00 sph 0.05 Full 186 a: 120, b: 245 Extinguished
M −18.00 sph 0.05 175 a: 177, b: 243
MOL0110 III:12 52 0.1 Full 185 a: 118, b: 221 Extinguished
M 0.05 210 a: 154, b: 239
MOL0110 III:14 51 −12.00 sph 0.1 Full 213 a: 173, b: 327 Extinguished
M −13.00 sph 0.1 204 a: 257, b: 380
MOL0110 III:18 41 High myopia 0.1 Full 164 a: 109, b: 258 Extinguished D15-RE deutan
M 0.07 191 a: 152, b: 277 LE scotopic lines
MOL0110 V:1 10 −5.00 sph 0.02 Short ND a: 226, b: 176 Severely reduced
M −4.00 sph 0.02 a:195, b: 160
MOL0110 V:2 5 0.05 Short ND a: 188, b: 185 Severely reduced and delayed
M 0.05 a:198, b: 163
8 −1.50/−1.75×7° 0.1 Short ND a: 45, b: 140 Extinguished
M −0.50/−1.25×5° 0.1 a: 51, b: 135
MOL0110 V:4 12 Full 334 a: 69, b: 316 Extinguished
M 382 a: 86, b: 283
MOL0110 V:8 6 pl/−1.50×10° 0.17 Full 273 a: 212, b: 269* Extinguished
M pl/−1.00*180° 0.17 221 a: 193, b: 424
MOL0110 V:9 8 Full 153 a: 162, b: 196 Extinguished
M 196 a: 184, b: 247
12 −.075/−2.00×180° 0.05 Full ND a: 144, b: 171 Severely reduced and delayed D15-mixed deutan/protan
M −.050/−2.00×0° 0.05 a: 200, b: 293
MOL0110 V:10 5 +7.00 sph 0.1 Short ND a: 154, b: 256 Extinguished
M +7.00 sph 0.1 a: 150, b: 310
9 +5.00/−1.50×30° 0.05 Full 239 a: 201, b: 372 Extinguished D15-mixed deutan/protan
M +6.00/−1.00×140° 0.05 236 a: 201, b: 327
MOL0110 V:11 5 Short ND a: 101, b: 254 Extinguished
M a: 105, b: 240
7 0.13 Short ND a: 22, b: 70 Extinguished
M 0.13 a: 38, b: 90
MOL0110 V:12 8 0.8 Full 243 a: 147, b: 243 Extinguished
M 0.8 226 a: 109, b: 242
MOL0110 V:20 22 −12.00 sph 0.12 Full 118 a: 119, b: 163 Extinguished D15-deutan
M −12.00 sph 0.12 122 a: 125, b: 157
MOL0110 V:27 7 −2.00/−2.00×5° 0.1 Short 287 a: 165, b: 350 6 37 D15-mixed deutan/protan
M pl/−2.00×180° 0.1 220 a: 215, b: 405 6 34
MOL0057 III:1 16 0.12 Full 14 42 D15-mixed deutan/protan
M 0.12
20 −18.00 sph 0.06 Full 80 a: 50, b: 226 Extinguished
M −18.00 sph 0.06 80 a: 56, b: 239
MOL0057 III:3 12 −6.00 sph 0.12 Full 219 a: 100 b: 300 Extinguished Protan
M −6.00 sph 0.12 246 a: 113 b: 297
MOL0250 III:2 50 −2.25/−0.25×97° 0.3 Full 340 a: 119 b: 382 21 32 D15-mixed deutan/protan
M −1.75/−1.25×109° 0.3 315 a: 142 b: 401 29 34
MOL0250 IV:3 24 −4.00/−0.75×120° 0.3 Full 243 a: 202 b: 331 40 27 D15-mixed deutan/protan
M −5.50/−1.50×75° 0.3 207 a: 213 b: 278 33 28
27 0.3 Full 189 a: 237 b: 331 27 27 D15-mixed deutan/protan
M 0.3 168 a: 200 b: 280 29 28
32 −2.75/−0.75×148° 0.25 Full 121 a: 118 b: 171 41 27 D15-mixed deutan/protan
M −5.00/−1.00×100° 0.2 110 a: 126 b: 181 29 29
MOL0267 III:1 34 0.3 Full 225 a: 296 b: 438 79 29 Ishihara-Deutan
M 0.3 209 a: 308 b: 407 74 29 D15-Deutan>Protan
MOL0283 II:4 24 0.25 Full 225 a: 175 b: 375 ND D15-Deutan
M 0.25 200 a: 140 b: 425
MOL0432 III:1 15 +1.00/−1.00×135° 0.2 Full 228 a: 128 b: 274 Extinguished D15-mixed deutan/protan
M +1.50/−1.50×45° 0.25 320 a: 216 b: 371
MOL0432 III:2 12 pl/−1.50×30° 0.3 Full 225 a: 181 b: 254 10 42 D15-Protan
M pl/−1.50×150° 0.3 209 a: 293 b: 294 6 45
MOL0152 III:1 7 −9.50/+3.25*115° 0.5 Short ND ND 20 39 ND
M −9.50/+4.50*60° 0.4 23 37
MOL0152 III:2 5 −5.50/+4.00*110° 0.2 Short ND ND 32 37 ND
M −6.50/+3.50*70° 0.1 31 37
MOL0152 III:3 5 −8.00/+2.75*140° 0.3 Short ND ND 20 39 ND
M −8.75/+2.75*50° 0.4 25 39
Female Carriers
MOL0110 IV:28 10 −11.00/−2.50×25° 0.4 Full 74 a: 51, b: 215 ND ND
F −11.00/−2.25×155° 0.4 148 a: 59, b: 254
MOL0110 V:7 7 Full 178 a: 191, b: 295
F 179 a: 263, b: 355 56 33
MOL0057 II:2 45 High myopia 1.0 Full 316 a: 110 b: 373 47 35 Normal
F 1.0 290 a: 118 b: 329 51 34
MOL0250 III:3 52 +2.00/−0.75×7° 1.25 Full 293 a: 162 b: 412 76 29 Normal
F +2.25/−1.25×174° 1.0 334 a: 141 b: 429 60 31
MOL0250 IV:2 24 −2.00/−1.25×150° 1.0 Full 338 a: 207 b: 458 83 28 Normal
F −2.00/−0.50×180° 1.0 384 a: 178 b: 463 69 28
MOL0250 IV:4 26 −0.75/−0.25×135° 1.0 Full 204 a: 138 b: nd 62 26 Normal
F −0.75 sph 1.0 254 a: 151 b: 434 62 27
Figure 2.
 
Retinal imaging of patients from families MOL0110 (A–F), MOL0283 (G–L), MOL0250 (M–Q), and MOL0267 (R–T) with XL cone opsin mutations. In MOL0110, funduscopy of a 13-year-old patient (MOL0110 V:4) did not reveal signs of maculopathy (A, LE), but some thinning of the foveal region was demonstrated by OCT (D–F), compared with normal OCT. 15 In a 51-year-old affected relative (MOL0110 III:14) with high myopia, fundus appearance (B) and FA examination (C) reflect myopic changes, but no overt signs of maculopathy or retinal dystrophy were apparent. Fundus photographs of patient MOL0283 II:4 with the novel cone opsin mutation c.358G>A (p.Val120Met) were presented at age 32 (G, H) and 41 (I–L). At age 32, a color fundus image showed mild atrophic changes in the foveal area (G, RE) with minimal changes on FA (H, RE). At age 41, progression of the maculopathy was evident, with increase in foveal atrophy (I, LE) and a window defect and staining on FA (J, LE). Autofluorescence abnormalities (K, RE) and subfoveal changes on OCT (L, LE) was also evident at age 41. Families MOL0250 (M–Q) and MOL0267 (R–T) shared the same cone opsin mutation (a single L opsin gene on the array harboring the LIAVS haplotype). Patient MOL0250 III:2 at the age of 50 showed minimal macular findings on fundus examination (M) and FA (N). His 32-year-old nephew, patient MOLO0250 IV:3, showed bilateral foveal atrophy, as seen on a color fundus photograph of the RE (O) and manifesting as a window defect in FA of the LE (P). Spectral OCT of the RE showed foveal thinning (Q). Patient MOL0267 III:1 at age 34 showed similar foveal thinning on OCT3 imaging of the RE (R, S) and LE (T).
Figure 2.
 
Retinal imaging of patients from families MOL0110 (A–F), MOL0283 (G–L), MOL0250 (M–Q), and MOL0267 (R–T) with XL cone opsin mutations. In MOL0110, funduscopy of a 13-year-old patient (MOL0110 V:4) did not reveal signs of maculopathy (A, LE), but some thinning of the foveal region was demonstrated by OCT (D–F), compared with normal OCT. 15 In a 51-year-old affected relative (MOL0110 III:14) with high myopia, fundus appearance (B) and FA examination (C) reflect myopic changes, but no overt signs of maculopathy or retinal dystrophy were apparent. Fundus photographs of patient MOL0283 II:4 with the novel cone opsin mutation c.358G>A (p.Val120Met) were presented at age 32 (G, H) and 41 (I–L). At age 32, a color fundus image showed mild atrophic changes in the foveal area (G, RE) with minimal changes on FA (H, RE). At age 41, progression of the maculopathy was evident, with increase in foveal atrophy (I, LE) and a window defect and staining on FA (J, LE). Autofluorescence abnormalities (K, RE) and subfoveal changes on OCT (L, LE) was also evident at age 41. Families MOL0250 (M–Q) and MOL0267 (R–T) shared the same cone opsin mutation (a single L opsin gene on the array harboring the LIAVS haplotype). Patient MOL0250 III:2 at the age of 50 showed minimal macular findings on fundus examination (M) and FA (N). His 32-year-old nephew, patient MOLO0250 IV:3, showed bilateral foveal atrophy, as seen on a color fundus photograph of the RE (O) and manifesting as a window defect in FA of the LE (P). Spectral OCT of the RE showed foveal thinning (Q). Patient MOL0267 III:1 at age 34 showed similar foveal thinning on OCT3 imaging of the RE (R, S) and LE (T).
Figure 3.
 
(A) Schematic representation and chromatogram of the region harboring the large genomic deletion of 46,217 bp that was found in family MOL0110. (B, C) The chromatogram of a novel missense mutation (p.Val120Met) identified in MOL0283-1 (B) and the corresponding amino acid alignment (C). (D) Genetic analysis of the LIAVA/S-related haplotypes. Represented chromatograms of exon 3 from a male normal control, a male patient with one gene on the array and the LIAVS haplotype, a female carrier of the LIAVS haplotype, and a male patient with the LIAVA haplotype on a hybrid gene are presented.
Figure 3.
 
(A) Schematic representation and chromatogram of the region harboring the large genomic deletion of 46,217 bp that was found in family MOL0110. (B, C) The chromatogram of a novel missense mutation (p.Val120Met) identified in MOL0283-1 (B) and the corresponding amino acid alignment (C). (D) Genetic analysis of the LIAVA/S-related haplotypes. Represented chromatograms of exon 3 from a male normal control, a male patient with one gene on the array and the LIAVS haplotype, a female carrier of the LIAVS haplotype, and a male patient with the LIAVA haplotype on a hybrid gene are presented.
To determine the frequency and spectrum of mutations and phenotypes caused by alterations in the L-M cone opsin gene array in our sample, we studied 17 additional families with cone-dominated disease in which the inheritance pattern was interpreted as definite XL (eight families), possible XL (6) or isolated male (3). Detailed PCR and sequencing analysis of the array revealed mutations in the opsin array that were likely pathogenic in five of the families (Table 1, Fig. 1). Sequence data of the remaining families are available in Supplementary Table S2. 
In family MOL0432 (Fig. 1), we identified a single hybrid L3/M4 gene (which included a 5′ L opsin sequence in exons 1 to 3 and a 3′ M opsin sequence in exons 4–6) harboring the previously described c.706C>T (p.Cys203Arg) missense mutation. Both affected siblings (III:1 and III:2) had low VAs (Table 2) at ages 15 and 12 years, respectively. Their rod ffERG amplitudes were within normal limits, mixed cone-rod ERG amplitudes were slightly reduced, and cone ERG was extinguished in one patient and was approximately 75% of the lower limit of normal in his brother. Fundus examination was within normal limits at these ages, but OCT revealed macular thinning. 
An isolated case (MOL0283 II:2, Fig. 1) of Iraqi Jewish ancestry had a single L opsin gene with a novel missense change, c.358G>A (p.Val120Met), in exon 2 (Fig. 3B). Sequence alignment showed that Val120 is a highly conserved amino acid among evolutionarily distant species (Fig. 3C). The mutation was not found in more than 140 control females of Iraqi Jewish origin. We therefore consider p.Val120Met to be a likely pathogenic mutation. Of interest, at the age of 32 years, early atrophic changes were seen on funduscopy (Fig. 2G) without a significant window defect or staining on FA (Fig. 2H). Nine years later, macular involvement progressed and was more evident, with clear evidence of atrophy on FA, subfoveal changes on OCT, and autofluorescence abnormalities (Figs. 2I–L). 
Patients from three additional families similarly had only a single opsin gene within the opsin gene array. This single gene harbored a rare combination of single nucleotide substitutions in exon 3 (Fig. 3D, Table 1, Supplementary Fig. S1A). An L opsin gene harboring the LIAVS (L153-I171-A174-V178-S180) haplotype (versus the most common L opsin haplotype LVAIS) was found in two of the families: MOL0250 and MOL0267. Patients from the third family, MOL0057, had a similar haplotype (LIAVA; Fig. 3D, Table 1), which differs by one amino acid at position 180 on an L3/M4 hybrid gene. These haplotypes contain two relatively rare substitutions, p.Val171Ile and p.Ile178Val, 18 and have been described as possibly causing disease in three families with BCM. 8,19,20 Of interest, the retinal phenotype in these patients was variable. The two affected brothers from family MOL0057 with the LIAVA haplotype had a relatively severe retinal phenotype compatible with BCM. They had high myopia, markedly impaired VA, moderately reduced mixed cone–rod ERG response, and extinguished cone ERGs (Table 2). Funduscopic findings included myopic, mildly pale optic discs, preserved retinal vessels, mottling of the RPE with very small spots of atrophy in the foveal region, and mild myopic changes in the periphery. In contrast, affected males from families MOL0250 and MOL0267 with the LIAVS haplotype had better visual function and somewhat different funduscopic findings. In family MOL0250, a 50-year-old affected male (III:2) had borderline normal dark-adapted mixed cone–rod ffERG responses, rod ERGs that were within normal limits, and cone ERGs reduced to ∼35% to 50% of the lower limit of normal. Mild atrophy was evident in the posterior pole around the fovea (Figs. 2M–N) and OCT showed thinning in the foveal region. His younger nephew (IV:3) showed progressive deterioration of VA and also rod ERG responses over the span of 8 years: mixed cone–rod ERG responses were moderately reduced, rod responses were still within normal limits, and cone ERGs reduced to 50% to 65% of the lower limit of normal. Both mixed and rod ERG responses deteriorated by ∼35% to 50% compared with the values recorded at age 24. Over this time, maculopathy also became more evident clinically. Areas of atrophy appeared in the center of the fovea, and the patient assumed parafoveal fixation loci. The foveal changes were not severe at the age of 24, but were clearly seen on fundus examination at the age of 32, with the atrophic areas evident on FA and marked thinning apparent on OCT (Figs. 2O–Q). The affected patient (III:1) from family MOL0267 had even better retinal function: At age 34, rod, mixed, and even cone ffERG responses were within normal limits. Funduscopic findings were minimal, but marked thinning of the foveal region was evident on OCT (Figs. 2R–T). 
Finally, we identified a family (MOL0152, Fig. 1) in which three affected brothers had a clinical diagnosis of XL-CRD. Sequencing analysis of the LCR, promoters, and all exons indicated that both the L and M opsin genes were present. Sequencing analysis of exon 3 revealed a mixture of both the common and the above-mentioned rare haplotype. To determine the order and composition of the opsin genes, we performed three long-range PCR amplifications aiming to analyze the most upstream gene, the remaining downstream gene(s), and the most downstream gene. Sequencing analysis of the three affected brothers revealed a 5′ L opsin gene harboring the LIAVA haplotype, followed by an M opsin gene (or a few identical M opsin genes) harboring the relatively common MVVVA haplotype in exon 3 (Fig. 1, Table 1, Supplementary Fig. S1A). The MVVVA haplotype has been reported in many control chromosomes 18,21 and is unlikely to cause dysfunction of the protein. The gene array in these three affected brothers is therefore likely to result in a dysfunctional L opsin protein (due to the LIAVA haplotype), but a rather normal M opsin function. 
The proximal subregion of the opsin gene array is known to contain DNA regulatory elements that are involved in controlling transcription of the opsin genes. 22 Sequence analysis of this region in our patients did not reveal the haplotype tag (represented by a C>T transition at position 152,928,238), which has been suggested to be associated with a relatively high L:M cone photoreceptor ratio. 
Discussion
We describe a spectrum of retinal phenotypes and mutations due to either the lack of intact L and M cone opsin genes or to the presence of a single, but abnormal, gene. Two of the mutations we describe are novel, including a large genomic deletion characterized in detail. It is intriguing to assume that a large set of different types of monoallelic mutations, such as the one found in the opsin gene array, may result in a clear genotype–phenotype correlation. Data provided by others, 7,8,10 as well as our data of family MOL0110, clearly indicate that when none of the opsins on the X-linked array is expressed (i.e., LCR deletions), or that when a nonfunctional opsin protein is expressed (i.e., p.Cys203Arg), 23 the resulting phenotype (usually referred to as BCM) is the most severe among the retinal phenotypes associated with X-linked cone opsin mutations. At the clinical level, this includes the lack of cone ERG response, severely impaired color vision, photophobia, and nystagmus. At the other end of the spectrum, when both the L and M opsin genes are present, a defect in one of the genes results in a relatively mild color vision deficiency with normal VA and ERG responses. The authors were not able to characterize the phenotypes in all cases between these two extremes, and there is no clear genotype–phenotype correlation. One of the most interesting mutations in the L-M opsin gene array is the combination of a rare set of amino acids within exon 3 leading to impaired cone function. We report two related haplotypes (LIAVS and LIAVA) in three Jewish families, two of whom are of Ashkenazi origin. In all cases, the cluster contained only one copy of a pigment gene (either L or L-M hybrid) harboring the haplotype (Supplementary Fig. S1A). Cone function in these patients was not absent (as is usually seen in patients with BCM) but rather was reduced to about one half of the lower limit of normal. These haplotypes have been reported in the literature, but the authors were not able to identify them in all cases as the cause of disease (Supplementary Fig. S1B). A similar haplotype (designated by the authors 8 as G1005A-G1007T-A1026G leading to 171I-178V) was initially reported in a single BCM family (family H) harboring a single L gene, but was not considered to be a pathogenic mutation at that time. 8 The cone ERG in two patients from family H was markedly decreased but not absent, even at the age of 50 years. In a later study, two brothers diagnosed with X-linked incomplete achromatopsia were found to carry two L genes and two M genes. 20 The two L opsin genes are likely to be the first genes on the array, and both harbored the LIAVA haplotype, considered by the authors to be the cause of disease. The phenotype is compatible with BCM although some residual M opsin cone function appeared to be present. The LIAVA haplotype has also been reported in dichromat individuals, but is not always recognized as the cause of color deficiency. A genetic analysis of 125 males with protan deficiency revealed an array that can explain the phenotype in most cases. 24 Among the cases considered by the authors to be carrying a normal array, one protanope individual (A376) harbored the LIAVA haplotype on the L gene (Supplementary Fig. S1B). In a different study, sequence analysis of 129 dichromats revealed two individuals harboring the rare haplotype: One deuteranope had an intact L gene and a single M gene with the LIAVA haplotype, and one protanope subject had a single L gene harboring the LIAVA haplotype and four M genes. The authors did not identify this haplotype in 300 pigment genes from normal control subjects and considered it likely to be pathogenic. 19 Indirect support for the pathogenicity of these haplotypes was obtained by the observation that the haplotype was not present in a set of 45 dichromats who carried a single X-linked opsin gene. 25 Although substitutions in amino acids 171 (two subjects) and 178 (five subjects) could be observed in this set of functional genes, 25 none carried both substitutions, and therefore none of the functional genes harbored the LIAVA/S haplotype. Eight disease-causing missense mutations were reported thus far to affect either the L or M opsin gene. 7,19,24,26 Their localization on a two-dimensional model of the L opsin protein (Fig. 4; gray-filled circles) show that they are spread along the protein. The amino acids composing the LIAVA/S haplotype are located mainly within TM4 in adjacent to tryptophan residues (codons 177 and 179) shown to be important for folding of the red opsin molecule. 27 In addition, helices IV and V were shown to be important for intradimeric contact in the process enabling rhodopsin to assemble into dimers. 28 The LIAVA/S haplotype may therefore reduce protein stability leading to a retinal phenotype. The novel mutation we identified, p.Val120Met, is located in the first extracellular loop and is conserved along evolution. A valine residue is also found at the same site in rhodopsin (as part of a relatively conserved region between rhodopsin and the L and M opsins) but no disease-causing mutations were reported to affect this amino acid. 
Figure 4.
 
Location of amino acid alterations reported thus far in the L and M cone opsin genes. Shaded areas: the transmembrane domains. Circles: amino acid differences and known polymorphisms with the more common amino acid (in a one-letter code); arrow: the amino acid change. The codon number is depicted for each change. Missense changes associated with a cone-opsin–related disease that are likely to cause protein dysfunction are on a gray background. The LIAVA haplotype is highlighted in black.
Figure 4.
 
Location of amino acid alterations reported thus far in the L and M cone opsin genes. Shaded areas: the transmembrane domains. Circles: amino acid differences and known polymorphisms with the more common amino acid (in a one-letter code); arrow: the amino acid change. The codon number is depicted for each change. Missense changes associated with a cone-opsin–related disease that are likely to cause protein dysfunction are on a gray background. The LIAVA haplotype is highlighted in black.
Most patients with BCM have a normal fundus appearance (even at advanced ages) and no cone ERG responses from an early age. In only a few cases, minor macular abnormalities could be observed. 1 It is interesting to note that the patients described with the LIAVA/S haplotype and the novel p.Val120Met probable disease-causing mutation had maculopathy, although their cone ERG was not absent (and was even normal in one patient). A possible explanation for this observation is that the lack of expression of both opsins causes cone dysfunction with no photoreceptor degeneration. On the other hand, an abnormal opsin could be partially functional but possibly toxic to the photoreceptor cell over time. This may cause cone photoreceptor degeneration that will initially affect the macula, but may at later stages cause rod degeneration as well. Adaptive optics techniques may help to determine cone photoreceptor distribution and survival in these patients at different retinal regions. In only one report so far, adaptive optics was used to assess the cone mosaic of dichromats, one of whom was a deuteranope due to an inactivating allele (haplotype LIAVA; Carroll J, personal communication, 2009) on the L opsin gene. 29 Patchy loss of normal cones throughout the photoreceptor mosaic was observed. A comparison of these data to the cone mosaic of patients with a variety of cone opsin array mutations may reveal the genotype–phenotype correlation at the cellular level. 
The clinical findings in family MOL0152 are more difficult to explain. Based on the cone opsin array genotype, the expected phenotype is protanopia, due to an abnormal L gene and a normal M opsin gene. The three patients in this family, however, had a more severe retinal phenotype, compatible with BCM, and all three patients had inherited the same cone opsin array from their mother. Other cases of cone-dominated disease (either BCM or progressive CD) have been reported to carry a deutan–protan genotype as well. 10,30,31 It is intriguing to consider the possibility that a skewed L/M cone photoreceptor ratio in combination with a deutan/protan genetic defect may lead to a severe retinal phenotype. High-resolution adaptive optics imaging identified a large variation in the L/M cone photoreceptors ratio (ranging from 1.1:1 to 16.5:1), even among individuals with normal VA and color vision. 32  
In summary, mutations in the X-linked array of cone opsin genes are considered to cause two main phenotypes: a relatively mild and highly prevalent phenotype (color vision deficiency) and a much more severe retinal disease, BCM. Based on our findings and as exemplified by the LIAVA/S haplotype, we propose that there is a spectrum of X-linked cone opsin phenotypes with different levels of severity between these two extremes. 
Supplementary Materials
Footnotes
 Supported in part by Grant 3000003241 from the Chief Scientist Office of the Ministry of Health, Israel; American Health Assistance Foundation Grant M2004-003; and the Yedidut1 Research Grant.
Footnotes
 Disclosure: L. Mizrahi-Meissonnier, None; S. Merin, None; E. Banin, None; D. Sharon, None
The authors thank Lina Bida for technical assistance, Ruhama Neis and Inbar Erdenist for performing the electrophysiological tests, Joseph Carroll for interesting and constructive discussions, and the patients and their family members for their cooperation. 
References
Kellner U Wissinger B Tippmann S . Blue cone monochromatism: clinical findings in patients with mutations in the red/green opsin gene cluster. Graefes Arch Clin Exp Ophthalmol. 2004;242:729–735. [CrossRef] [PubMed]
Michaelides M Johnson S Simunovic MP . Blue cone monochromatism: a phenotype and genotype assessment with evidence of progressive loss of cone function in older individuals. Eye. 2005;19:2–10. [CrossRef] [PubMed]
Demirci FY Rigatti BW Wen G . X-Linked cone-rod Dystrophy (locus COD1): identification of mutations in RPGR exon ORF15. Am J Hum Genet. 2002;70:1049–1053. [CrossRef] [PubMed]
Yang Z Peachey NS Moshfeghi DM . Mutations in the RPGR gene cause X-linked cone dystrophy. Hum Mol Genet. 2002;11:605–611. [CrossRef] [PubMed]
Ayyagari R Demirci F Liu J . X-Linked recessive atrophic macular degeneration from RPGR mutation. Genomics. 2002;80:166–171. [CrossRef] [PubMed]
Sharon D Sandberg MA Rabe VW . RP2 and RPGR mutations and clinical correlations in patients with X-linked retinitis pigmentosa. Am J Hum Genet. 2003;73:1131–1146. [CrossRef] [PubMed]
Nathans J Maumenee IH Zrenner E . Genetic heterogeneity among blue-cone monochromats. Am J Hum Genet. 1993;53:987–1000. [PubMed]
Nathans J Davenport CM Maumenee IH . Molecular genetics of human blue cone monochromacy. Science. 1989;245:831–838. [CrossRef] [PubMed]
Nathans J Piantanida TP Eddy RL Shows TB Hogness DS . Molecular genetics of inherited variation in human color vision. Science. 1986;232:203–210. [CrossRef] [PubMed]
Ayyagari R Kakuk LE Bingham EL . Spectrum of color gene deletions and phenotype in patients with blue cone monochromacy. Hum Genet. 2000;107:75–82. [CrossRef] [PubMed]
Reyniers E Van Thienen MN Meire F . Gene conversion between red and defective green opsin gene in blue cone monochromacy. Genomics. 1995;29:323–328. [CrossRef] [PubMed]
Gardner JC Michaelides M Holder GE . Blue cone monochromacy: causative mutations and associated phenotypes. Mol Vis. 2009;15:876–884. [PubMed]
Ladekjaer-Mikkelsen AS Rosenberg T Jorgensen AL . A new mechanism in blue cone monochromatism. Hum Genet. 1996;98:403–408. [CrossRef] [PubMed]
Banin E Shalev RS Obolensky A . Retinal function abnormalities in patients treated with vigabatrin. Arch Ophthalmol. 2003;121:811–816. [CrossRef] [PubMed]
Chan A Duker JS Ko TH Fujimoto JG Schuman JS . Normal macular thickness measurements in healthy eyes using Stratus optical coherence tomography. Arch Ophthalmol. 2006;124:193–198. [CrossRef] [PubMed]
Hayashi T Motulsky AG Deeb SS . Position of a ‘green-red’ hybrid gene in the visual pigment array determines colour-vision phenotype. Nat Genet. 1999;22:90–93. [CrossRef] [PubMed]
Oda S Ueyama H Tanabe S . Detection of female carriers of congenital color-vision deficiencies by visual pigment gene analysis. Curr Eye Res. 2000;21:767–773. [CrossRef] [PubMed]
Winderickx J Battisti L Hibiya Y Motulsky AG Deeb SS . Haplotype diversity in the human red and green opsin genes: evidence for frequent sequence exchange in exon 3. Hum Mol Genet. 1993;2:1413–1421. [CrossRef] [PubMed]
Neitz M Carroll J Renner A . Variety of genotypes in males diagnosed as dichromatic on a conventional clinical anomaloscope. Vis Neurosci. 2004;21:205–216. [CrossRef] [PubMed]
Crognale MA Fry M Highsmith J . Characterization of a novel form of X-linked incomplete achromatopsia. Vis Neurosci. 2004;21:197–203. [CrossRef] [PubMed]
Deeb SS Alvarez A Malkki M Motulsky AG . Molecular patterns and sequence polymorphisms in the red and green visual pigment genes of Japanese men. Hum Genet. 1995;95:501–506. [CrossRef] [PubMed]
Gunther KL Neitz J Neitz M . Nucleotide polymorphisms upstream of the X-chromosome opsin gene array tune L:M cone ratio. Vis Neurosci. 2008;25:265–271. [CrossRef] [PubMed]
Kazmi MA Sakmar TP Ostrer H . Mutation of a conserved cysteine in the X-linked cone opsins causes color vision deficiencies by disrupting protein folding and stability. Invest Ophthalmol Vis Sci. 1997;38:1074–1081. [PubMed]
Ueyama H Kuwayama S Imai H . Analysis of L-cone/M-cone visual pigment gene arrays in Japanese males with protan color-vision deficiency. Vision Res. 2004;44:2241–2252. [CrossRef] [PubMed]
Sharpe LT Stockman A Jagle H . Red, green, and red-green hybrid pigments in the human retina: correlations between deduced protein sequences and psychophysically measured spectral sensitivities. J Neurosci. 1998;18:10053–10069. [PubMed]
Ueyama H Kuwayama S Imai H . Novel missense mutations in red/green opsin genes in congenital color-vision deficiencies. Biochem Biophys Res Commun. 2002;294:205–209. [CrossRef] [PubMed]
Nakayama T Zhang W Cowan A Kung M . Mutagenesis studies of human red opsin: trp-281 is essential for proper folding and protein-retinal interactions. Biochemistry. 1998;37:17487–17494. [CrossRef] [PubMed]
Liang Y Fotiadis D Filipek S . Organization of the G protein-coupled receptors rhodopsin and opsin in native membranes. J Biol Chem. 2003;278:21655–21662. [CrossRef] [PubMed]
Carroll J Neitz M Hofer H Neitz J Williams DR . Functional photoreceptor loss revealed with adaptive optics: an alternate cause of color blindness. Proc Natl Acad Sci U S A. 2004;101:8461–8466. [CrossRef] [PubMed]
Kellner U Sadowski B Zrenner E Foerster MH . Selective cone dystrophy with protan genotype. Invest Ophthalmol Vis Sci. 1995;36:2381–2387. [PubMed]
Scholl HP Kremers J Besch D Zrenner E Jagle H . Progressive cone dystrophy with deutan genotype and phenotype. Graefes Arch Clin Exp Ophthalmol. 2006;244:183–191. [CrossRef] [PubMed]
Hofer H Carroll J Neitz J Neitz M Williams DR . Organization of the human trichromatic cone mosaic. J Neurosci. 2005;25:9669–9679. [CrossRef] [PubMed]
Figure 1.
 
Families with mutations in the X-linked cone opsin gene array. Numbers above the family tree indicate family serial number, numbers within symbols indicate number of siblings, numbers below symbols indicate generation and individual numbers, arrows indicate index cases, and a dot within a circle designates an obligate carrier. M1 to M6 designate mutations identified in each family: M1, L3/M4 LIAVA; M2, L opsin LIAVA with a normal M opsin gene; M3, L opsin LIAVA; M4, L opsin p.Val120Met; M5, L3/M4 p.Cys203Arg; and M6, c.9_OPN1MW:578+271del46217.
Figure 1.
 
Families with mutations in the X-linked cone opsin gene array. Numbers above the family tree indicate family serial number, numbers within symbols indicate number of siblings, numbers below symbols indicate generation and individual numbers, arrows indicate index cases, and a dot within a circle designates an obligate carrier. M1 to M6 designate mutations identified in each family: M1, L3/M4 LIAVA; M2, L opsin LIAVA with a normal M opsin gene; M3, L opsin LIAVA; M4, L opsin p.Val120Met; M5, L3/M4 p.Cys203Arg; and M6, c.9_OPN1MW:578+271del46217.
Figure 2.
 
Retinal imaging of patients from families MOL0110 (A–F), MOL0283 (G–L), MOL0250 (M–Q), and MOL0267 (R–T) with XL cone opsin mutations. In MOL0110, funduscopy of a 13-year-old patient (MOL0110 V:4) did not reveal signs of maculopathy (A, LE), but some thinning of the foveal region was demonstrated by OCT (D–F), compared with normal OCT. 15 In a 51-year-old affected relative (MOL0110 III:14) with high myopia, fundus appearance (B) and FA examination (C) reflect myopic changes, but no overt signs of maculopathy or retinal dystrophy were apparent. Fundus photographs of patient MOL0283 II:4 with the novel cone opsin mutation c.358G>A (p.Val120Met) were presented at age 32 (G, H) and 41 (I–L). At age 32, a color fundus image showed mild atrophic changes in the foveal area (G, RE) with minimal changes on FA (H, RE). At age 41, progression of the maculopathy was evident, with increase in foveal atrophy (I, LE) and a window defect and staining on FA (J, LE). Autofluorescence abnormalities (K, RE) and subfoveal changes on OCT (L, LE) was also evident at age 41. Families MOL0250 (M–Q) and MOL0267 (R–T) shared the same cone opsin mutation (a single L opsin gene on the array harboring the LIAVS haplotype). Patient MOL0250 III:2 at the age of 50 showed minimal macular findings on fundus examination (M) and FA (N). His 32-year-old nephew, patient MOLO0250 IV:3, showed bilateral foveal atrophy, as seen on a color fundus photograph of the RE (O) and manifesting as a window defect in FA of the LE (P). Spectral OCT of the RE showed foveal thinning (Q). Patient MOL0267 III:1 at age 34 showed similar foveal thinning on OCT3 imaging of the RE (R, S) and LE (T).
Figure 2.
 
Retinal imaging of patients from families MOL0110 (A–F), MOL0283 (G–L), MOL0250 (M–Q), and MOL0267 (R–T) with XL cone opsin mutations. In MOL0110, funduscopy of a 13-year-old patient (MOL0110 V:4) did not reveal signs of maculopathy (A, LE), but some thinning of the foveal region was demonstrated by OCT (D–F), compared with normal OCT. 15 In a 51-year-old affected relative (MOL0110 III:14) with high myopia, fundus appearance (B) and FA examination (C) reflect myopic changes, but no overt signs of maculopathy or retinal dystrophy were apparent. Fundus photographs of patient MOL0283 II:4 with the novel cone opsin mutation c.358G>A (p.Val120Met) were presented at age 32 (G, H) and 41 (I–L). At age 32, a color fundus image showed mild atrophic changes in the foveal area (G, RE) with minimal changes on FA (H, RE). At age 41, progression of the maculopathy was evident, with increase in foveal atrophy (I, LE) and a window defect and staining on FA (J, LE). Autofluorescence abnormalities (K, RE) and subfoveal changes on OCT (L, LE) was also evident at age 41. Families MOL0250 (M–Q) and MOL0267 (R–T) shared the same cone opsin mutation (a single L opsin gene on the array harboring the LIAVS haplotype). Patient MOL0250 III:2 at the age of 50 showed minimal macular findings on fundus examination (M) and FA (N). His 32-year-old nephew, patient MOLO0250 IV:3, showed bilateral foveal atrophy, as seen on a color fundus photograph of the RE (O) and manifesting as a window defect in FA of the LE (P). Spectral OCT of the RE showed foveal thinning (Q). Patient MOL0267 III:1 at age 34 showed similar foveal thinning on OCT3 imaging of the RE (R, S) and LE (T).
Figure 3.
 
(A) Schematic representation and chromatogram of the region harboring the large genomic deletion of 46,217 bp that was found in family MOL0110. (B, C) The chromatogram of a novel missense mutation (p.Val120Met) identified in MOL0283-1 (B) and the corresponding amino acid alignment (C). (D) Genetic analysis of the LIAVA/S-related haplotypes. Represented chromatograms of exon 3 from a male normal control, a male patient with one gene on the array and the LIAVS haplotype, a female carrier of the LIAVS haplotype, and a male patient with the LIAVA haplotype on a hybrid gene are presented.
Figure 3.
 
(A) Schematic representation and chromatogram of the region harboring the large genomic deletion of 46,217 bp that was found in family MOL0110. (B, C) The chromatogram of a novel missense mutation (p.Val120Met) identified in MOL0283-1 (B) and the corresponding amino acid alignment (C). (D) Genetic analysis of the LIAVA/S-related haplotypes. Represented chromatograms of exon 3 from a male normal control, a male patient with one gene on the array and the LIAVS haplotype, a female carrier of the LIAVS haplotype, and a male patient with the LIAVA haplotype on a hybrid gene are presented.
Figure 4.
 
Location of amino acid alterations reported thus far in the L and M cone opsin genes. Shaded areas: the transmembrane domains. Circles: amino acid differences and known polymorphisms with the more common amino acid (in a one-letter code); arrow: the amino acid change. The codon number is depicted for each change. Missense changes associated with a cone-opsin–related disease that are likely to cause protein dysfunction are on a gray background. The LIAVA haplotype is highlighted in black.
Figure 4.
 
Location of amino acid alterations reported thus far in the L and M cone opsin genes. Shaded areas: the transmembrane domains. Circles: amino acid differences and known polymorphisms with the more common amino acid (in a one-letter code); arrow: the amino acid change. The codon number is depicted for each change. Missense changes associated with a cone-opsin–related disease that are likely to cause protein dysfunction are on a gray background. The LIAVA haplotype is highlighted in black.
Table 1.
 
Families with Identified Mutations In the L-M Cone Opsin Gene Array
Table 1.
 
Families with Identified Mutations In the L-M Cone Opsin Gene Array
Family Genes Opsin Gene Sequence* Mutation
Exon 2 Exon 3 Exon 4 Exon 5
65 111 116 120 153 171 174 178 180 203 230 233 236 274 275 277 279 285 298 309
L-wt† T I S V L/M V/I A/V I/V S/A C I/T A/S M/V I F Y V T A Y
% 67 89 93 96 56 97 97 88
M-wt† I/T V Y V M/L V A/V I/V A/S C T S V V L F F A P F
% 98 90 71 71 96
MOL0057 L3/M4 T I S V L I A V A C T S V V L F F A P F L3/M4 gene with the LIAVA haplotype
MOL0110 No intact gene NA NA C T S V V L F F A P F c.9_OPN1MW:578+ 271del46217
MOL0250 L T I S V L I A V S C I A M I F Y V T A Y L gene with the LIAVS haplotype
MOL0267 L T I S V L I A V S C I A M I F Y V T A Y L gene with the LIAVS haplotype
MOL0283 L T I S M L V V I S C I A M I F Y V T A Y c.358G>A (p.Val120Met)
MOL0432 L3/M4 T I S V L V A I A R T S V V L F F A P F c.706C>T (p.Cys203Arg)
MOL0152 L+M T/I I/V S/Y V L/M I/V A/V V/V A/A C I/T A/S M/V I/V F/L Y/F V/F T/A P Y/F L gene with the LIAVA haplotype‡
Table 2.
 
Clinical Data of Affected Males and Female Carriers with Mutations in the L and M Cone Opsin Array
Table 2.
 
Clinical Data of Affected Males and Female Carriers with Mutations in the L and M Cone Opsin Array
Patient Age Sex Refraction* Visual Acuity ffERG Protocol† FFERG Rod (μV)† ffERG Mixed Cone-Rod (μV)† ffERG Cone† Color Vision§
Amp (μV) IT (mS)
Affected Males
MOL0110 III:2 44 −18.00 sph 0.05 Full 186 a: 120, b: 245 Extinguished
M −18.00 sph 0.05 175 a: 177, b: 243
MOL0110 III:12 52 0.1 Full 185 a: 118, b: 221 Extinguished
M 0.05 210 a: 154, b: 239
MOL0110 III:14 51 −12.00 sph 0.1 Full 213 a: 173, b: 327 Extinguished
M −13.00 sph 0.1 204 a: 257, b: 380
MOL0110 III:18 41 High myopia 0.1 Full 164 a: 109, b: 258 Extinguished D15-RE deutan
M 0.07 191 a: 152, b: 277 LE scotopic lines
MOL0110 V:1 10 −5.00 sph 0.02 Short ND a: 226, b: 176 Severely reduced
M −4.00 sph 0.02 a:195, b: 160
MOL0110 V:2 5 0.05 Short ND a: 188, b: 185 Severely reduced and delayed
M 0.05 a:198, b: 163
8 −1.50/−1.75×7° 0.1 Short ND a: 45, b: 140 Extinguished
M −0.50/−1.25×5° 0.1 a: 51, b: 135
MOL0110 V:4 12 Full 334 a: 69, b: 316 Extinguished
M 382 a: 86, b: 283
MOL0110 V:8 6 pl/−1.50×10° 0.17 Full 273 a: 212, b: 269* Extinguished
M pl/−1.00*180° 0.17 221 a: 193, b: 424
MOL0110 V:9 8 Full 153 a: 162, b: 196 Extinguished
M 196 a: 184, b: 247
12 −.075/−2.00×180° 0.05 Full ND a: 144, b: 171 Severely reduced and delayed D15-mixed deutan/protan
M −.050/−2.00×0° 0.05 a: 200, b: 293
MOL0110 V:10 5 +7.00 sph 0.1 Short ND a: 154, b: 256 Extinguished
M +7.00 sph 0.1 a: 150, b: 310
9 +5.00/−1.50×30° 0.05 Full 239 a: 201, b: 372 Extinguished D15-mixed deutan/protan
M +6.00/−1.00×140° 0.05 236 a: 201, b: 327
MOL0110 V:11 5 Short ND a: 101, b: 254 Extinguished
M a: 105, b: 240
7 0.13 Short ND a: 22, b: 70 Extinguished
M 0.13 a: 38, b: 90
MOL0110 V:12 8 0.8 Full 243 a: 147, b: 243 Extinguished
M 0.8 226 a: 109, b: 242
MOL0110 V:20 22 −12.00 sph 0.12 Full 118 a: 119, b: 163 Extinguished D15-deutan
M −12.00 sph 0.12 122 a: 125, b: 157
MOL0110 V:27 7 −2.00/−2.00×5° 0.1 Short 287 a: 165, b: 350 6 37 D15-mixed deutan/protan
M pl/−2.00×180° 0.1 220 a: 215, b: 405 6 34
MOL0057 III:1 16 0.12 Full 14 42 D15-mixed deutan/protan
M 0.12
20 −18.00 sph 0.06 Full 80 a: 50, b: 226 Extinguished
M −18.00 sph 0.06 80 a: 56, b: 239
MOL0057 III:3 12 −6.00 sph 0.12 Full 219 a: 100 b: 300 Extinguished Protan
M −6.00 sph 0.12 246 a: 113 b: 297
MOL0250 III:2 50 −2.25/−0.25×97° 0.3 Full 340 a: 119 b: 382 21 32 D15-mixed deutan/protan
M −1.75/−1.25×109° 0.3 315 a: 142 b: 401 29 34
MOL0250 IV:3 24 −4.00/−0.75×120° 0.3 Full 243 a: 202 b: 331 40 27 D15-mixed deutan/protan
M −5.50/−1.50×75° 0.3 207 a: 213 b: 278 33 28
27 0.3 Full 189 a: 237 b: 331 27 27 D15-mixed deutan/protan
M 0.3 168 a: 200 b: 280 29 28
32 −2.75/−0.75×148° 0.25 Full 121 a: 118 b: 171 41 27 D15-mixed deutan/protan
M −5.00/−1.00×100° 0.2 110 a: 126 b: 181 29 29
MOL0267 III:1 34 0.3 Full 225 a: 296 b: 438 79 29 Ishihara-Deutan
M 0.3 209 a: 308 b: 407 74 29 D15-Deutan>Protan
MOL0283 II:4 24 0.25 Full 225 a: 175 b: 375 ND D15-Deutan
M 0.25 200 a: 140 b: 425
MOL0432 III:1 15 +1.00/−1.00×135° 0.2 Full 228 a: 128 b: 274 Extinguished D15-mixed deutan/protan
M +1.50/−1.50×45° 0.25 320 a: 216 b: 371
MOL0432 III:2 12 pl/−1.50×30° 0.3 Full 225 a: 181 b: 254 10 42 D15-Protan
M pl/−1.50×150° 0.3 209 a: 293 b: 294 6 45
MOL0152 III:1 7 −9.50/+3.25*115° 0.5 Short ND ND 20 39 ND
M −9.50/+4.50*60° 0.4 23 37
MOL0152 III:2 5 −5.50/+4.00*110° 0.2 Short ND ND 32 37 ND
M −6.50/+3.50*70° 0.1 31 37
MOL0152 III:3 5 −8.00/+2.75*140° 0.3 Short ND ND 20 39 ND
M −8.75/+2.75*50° 0.4 25 39
Female Carriers
MOL0110 IV:28 10 −11.00/−2.50×25° 0.4 Full 74 a: 51, b: 215 ND ND
F −11.00/−2.25×155° 0.4 148 a: 59, b: 254
MOL0110 V:7 7 Full 178 a: 191, b: 295
F 179 a: 263, b: 355 56 33
MOL0057 II:2 45 High myopia 1.0 Full 316 a: 110 b: 373 47 35 Normal
F 1.0 290 a: 118 b: 329 51 34
MOL0250 III:3 52 +2.00/−0.75×7° 1.25 Full 293 a: 162 b: 412 76 29 Normal
F +2.25/−1.25×174° 1.0 334 a: 141 b: 429 60 31
MOL0250 IV:2 24 −2.00/−1.25×150° 1.0 Full 338 a: 207 b: 458 83 28 Normal
F −2.00/−0.50×180° 1.0 384 a: 178 b: 463 69 28
MOL0250 IV:4 26 −0.75/−0.25×135° 1.0 Full 204 a: 138 b: nd 62 26 Normal
F −0.75 sph 1.0 254 a: 151 b: 434 62 27
Supplementary Table S1
Supplementary Table S2
Supplementary Figure S1
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×