Abstract
Purpose: :
We describe a series of patients with peripapillary pigmentary retinal dystrophy with a unique phenotype distinct from classical retinitis pigmentosa. Our aims were to screen these patients for mutations in the novel transcription enhancer gene, TEAD1, and the rhodopsin (RHO) gene and to characterize their phenotype. TEAD1 and RHO gene were chosen as a missense mutation in TEAD1 has recently been found in patients with helicoid peripapillary chorioretinal degeneration, while heterozygous missense mutation in the rhodopsin gene is the most common molecular cause of regional retinitis pigmentosa.
Methods: :
Eight (seven Chinese and one Malay) patients with clinically diagnosed peripapillary pigmentary retinal dystrophy were identified and recruited into the study. The 13 exons of the TEAD1 gene and the 5 exons of the RHO gene were amplified via polymerase chain reaction and subjected to bi–directional sequencing using BigDye Terminator v3.1 chemistries and analyzed on an ABI PRISM 3100 Genetic Analyzer. Detailed characterization of the patients' phenotype was performed with fundal photography, visual field testing, fundal fluorescein angiography and electroretinography(ERG).
Results: :
Our patients had severe phenotypes. Symptoms of decreased vision and nyctalopia began as early as the second decade of life. Well–demarcated peripapillary retinal dystrophy with minimal pigmentation were seen in both eyes. Patients with macular involvement had resultant poor visual acuity. Visual field defects were symmetrical and correlated with fundal findings. Full–field ERG showed no responses and fundal fluorescein angiography revealed corresponding window defects. We identified a novel heterozygous substitution (A169T) in rhodopsin. Controls are currently being analyzed to ascertain the pathogenicity of this variation. Screening of TEAD1 has not yet revealed any pathogenic changes.
Conclusions: :
Our patients with peripapillary pigmentary dystrophy had a severe unique phenotype. A hitherto unreported possible pathogenic change has been identified in rhodopsin.
Keywords: retinal degenerations: hereditary • gene screening • mutations