Common polymorphisms of the CFH, LOC 387715/ARMS2 and HTRA1 genes may not influence the intra-familial variability of X-linked juvenile retinoschisis

X-linked juvenile retinoschisis (XLRS) is the leading cause of juvenile macular degeneration in males and is rare in females. Previous studies have shown that there is a marked intra- and inter-familial variation in disease severity and progression. This suggests that additional factors, such as genetic modifiers and environmental elements, influence disease severity. In order to understand the contribution of genetic modifiers, we aimed to ascertain whether common variants of the CFH, LOC 387715/ARMS2 and HTRA1 genes, which are major risk factors in age-related macular degeneration, contribute to the phenotypic variability of the XLRS disorder. Two unrelated XLRS families were selected, one harboring the missense mutation and the second a nonsense mutation in the RS gene. Both families exhibited variations in clinical phenotype. Genomic DNA from family members were analyzed for the above three genes using the polymerase chain reaction-based restriction fragment length polymorphism method. Our analyses revealed that both families were wild-type with respect to the LOC 387715/ARMS2 and HTRA1 genes. In one family (but not the other), the most severely affected and unaffected individuals were heterozygous for the CFH polymorphisms, while the less severely affected individual was wild-type. However, this alteration did not necessarily influence disease severity. Although we cannot completely rule out the role of the above genes in determining the phenotypic variability of the disorder, and though the statistical significance of the results could not be assessed due to the small scale of the study, it is unlikely that common polymorphisms of the CFH, LOC 387715/ARMS2 and HTRA1 genes serve as disease modifiers of the XLRS disorder.