Abstract
Purpose::
To describe the clinical characteristics of a new ophthalmic syndrome which consists of posterior microphthalmos, retinitis pigmentosa, foveoschisis, and optic disc drusen that segregates as an autosomal recessive trait in a family with four affected sibs. The MFRP and CHX10 genes, previously implicated in autosomal recessive forms of nanophthalmos/microphthalmos, were analyzed as candidate genes for this novel disease.
Methods::
Complete ophthalmologic examinations were performed in all affected sibs and their parents. Deoxyribonucleic acid from blood was extracted from each consenting family member to determine the status of their MFRP and CHX10 genes. The coding regions of both genes were amplified by PCR and analyzed for mutations using fluorescent nucleotide sequencing.
Results::
In all affected siblings, ophthalmologic examination demonstrated normal horizontal corneal diameters and high hyperopia; funduscopy, ERG, and FA evidenced a progressive retinal dystrophy compatible with retinitis pigmentosa; A- and B-mode ultrasonography revealed decreased axial eye length and optic disc drusen; OCT showed localized macular retinoschisis. MFRP molecular analysis disclosed a one base pair insertion in exon 5 (c.498_499insC) in all affected individuals, a mutation that predicts a truncated protein (P165fsX198). Both parents were heterozygous for this mutation.
Conclusions::
A distinct autosomal recessive ophthalmic syndrome characterized by microphthalmos, retinitis pigmentosa, foveoschisis, and optic disc drusen is described. We demonstrated that this clinical association is caused by a mutation in MFRP, a gene previously implicated in isolated nanophthalmos. Our data indicate that defects in MFRP could be responsible for syndromic forms of microphthalmos/retinal degeneration and that this gene is necessary for photoreceptor maintenance.
Keywords: gene mapping • degenerations/dystrophies • retinal degenerations: hereditary