Analysis of peripherin/RDS gene for Japanese retinal dystrophies

Genetic and Phenotypic Landscape of PRPH2-Associated Retinal Dystrophy in Japan

Peripherin-2 (PRPH2) is one of the causative genes of inherited retinal dystrophy. While the gene is relatively common in Caucasians, reports from Asian ethnicities are limited. In the present study, we report 40 Japanese patients from 30 families with PRPH2-associated retinal dystrophy. We identified 17 distinct pathogenic or likely pathogenic variants using next-generation sequencing. Variants p.R142W and p.V200E were relatively common in the cohort. The age of onset was generally in the 40’s; however, some patients had earlier onset (age: 5 years). Visual acuity of the patients ranged from hand motion to 1.5 (Snellen equivalent 20/13). The patients showed variable phenotypes such as retinitis pigmentosa, cone-rod dystrophy, and macular dystrophy. Additionally, intrafamilial phenotypic variability was observed. Choroidal neovascularization was observed in three eyes of two patients with retinitis pigmentosa. The results demonstrate the genotypic and phenotypic variations of the disease in the Asian cohort.

The spectrum of retinal dystrophies caused by mutations in the peripherin/RDS gene

Peripherin/rds is an integral membrane glycoprotein, mainly located in the rod and cone outer segments. The relevance of this protein to photoreceptor outer segment morphology was first demonstrated in retinal degeneration slow (rds) mice. Thus far, over 90 human peripherin/RDS gene mutations have been identified. These mutations have been associated with a variety of retinal dystrophies, in which there is a remarkable inter- and intrafamilial variation of the retinal phenotype. In this paper, we discuss the characteristics of the peripherin/RDS gene and its protein product. An overview is presented of the broad spectrum of clinical phenotypes caused by human peripherin/RDS gene mutations, ranging from various macular dystrophies to widespread forms of retinal dystrophy such as retinitis pigmentosa. Finally, we review the proposed genotype-phenotype correlation and the pathophysiologic mechanisms underlying this group of retinal dystrophies.

Intrafamilial clinical heterogeneity associated with a novel mutation of the retinal degeneration slow/peripherin gene

AIMS

To identify the phenotypic variations in 6 related individuals affected by a novel mutation in the retinal degeneration slow/peripherin gene.

METHODS

Ten family members underwent ophthalmologic assessment with slit-lamp biomicroscopy, dilated fundus examination, fundus photography, autofluorescence imaging and electrophysiological tests. Genomic DNA was extracted from blood samples of all family members (n = 15) using the standard salting-out procedure.

RESULTS

The novel C165R mutation was identified in 8 individuals. Of these 8 patients, only 6 gave consent to the clinical study. They had a retinal disease characterized by an adulthood onset of symptoms, and their best corrected visual acuity was between 20/50 and 20/20. Fundus examination showed that 3 patients had typical fundus flavimaculatus: 1 had butterfly-shaped pattern dystrophy and 2 had incipient retinal changes.

CONCLUSION

We identified a novel mutation of the retinal degeneration slow/peripherin gene in a family affected by different patterns of retinal dystrophy. This is the first report of an association of fundus flavimaculatus with butterfly-shaped pattern dystrophy.

Evaluation of the ELOVL4 gene in a Chinese family with autosomal dominant STGD3-like macular dystrophy

Stargardt disease-3 (STGD3) is an autosomal dominant juvenile-onset macular dystrophy characterized by progressive decreasing visual acuity, bilateral atrophic changes in the macula and absence of characteristic dark choroids. We identified a STGD3-like macular dystrophy pedigree by clinical examination. To explore whether the STGD3-like phenotype in the kindred is linked to ELOVL4 gene or associated with any other identified STGD gene, we extracted genomic DNA from leukocytes of peripheral blood from the available family members and 50 normal controls for mutation analysis. Then the exons of ELOVL4, RDS and the three exons of ABCR were amplified by polymerase chain reaction (PCR). All PCR products were screened for mutations by combination of denaturing high-performance liquid chromatography (DHPLC) analysis and DNA sequencing. No mutation was found in the exons of three candidate genes, but we obtained three non-pathogenic polymorphisms, IVS5-2533T-->A in ELOVL4, 558C-->T (Val106Val) and 1150G-->C (Glu304Gln) in RDS. And IVS5-2533T-->A is never shown in the previous references. These data suggested that there exist other unknown genes responsible for the STGD3-like phenotype in the pedigree.