Phenotype - Genotype Correlation in Patients With Retinal Degenerations

Abstract

Purpose: : To describe the association between genotype and phenotype in patients with inherited retinal degenerations (RD).

Methods: : Five families with RD were analyzed: two with a possible diagnosis of Best macular degeneration, one each with dominant and recessive retinitis pigmentosa and one with a clinical diagnosis of Doyne’s honeycomb dystrophy. The phenotype of these families was characterized by measuring visual acuities, visual fields, ERG, EOG, fundus photography, color vision testing and fluorescein angiography. Genetic analysis was carried out by screening for mutations in candidate genes using PCR and sequencing.

Results: : One patient with Best macular dystrophy had two mutations in the bestrophin gene in the heterozygous state. A homozygous mutation in the bestrophin gene was detected in siblings from an unrelated family. The clinical symptoms differed in members of these families carrying bestrophin mutations in the homozygous and heterozygous state. A homozygous nonsense mutation in the CERKL gene was identified in a family with three sisters affected with recessive retinitis pigmentosa (RP). The clinical status in these patients was followed for 17 years from the onset of clinical symptoms in the second decade. The phenotype of a dominant RP family with 7 affected members with a mutation in the IMPDH1 gene was notable for onset of disease in the 3^rd decade, marked optic atrophy without bone spicules and no pigment clumping. A novel potentially pathogenic change in the EFEMP1 gene was found in a patient with typical symptoms of Doyne’s honeycomb dystrophy with onset of symptoms in the 2^nd decade. Family history showed a father with age-related macular degeneration.

Conclusions: : The molecular basis of disease in these families allowed definition of the phenotype associated with genotypes observed in these families.

Keywords: genetics