Abstract
Purpose::
To test whether the complement factor H (CFH) polymorphism associated with risk of age-related macular degeneration is also a factor affecting the retinal phenotype found in individuals with the RDS IVS 2+3 A→T mutation which results in highly-variable, dominant-acting retinitis pigmentosa (RP) and/or maculopathy.
Methods::
Thirty-nine individuals with the RDS IVS 2+3 A→T mutation (including members from 15 independently ascertained families, but all carrying the same disease gene haplotype) were sequenced for the CFH T→C polymorphism which results in the Tyr402His amino acid change. Phenotypes were characterized based on examination of fundus photographs, electroretinogram (ERG) data (if available), and other pertinent medical and ophthalmic information and put into one of three categories: retinitis pigmentosa (RP), pattern dystrophy (PD), or central areolar choroidal dystrophy (CACD). Association was evaluated using a Fisher exact test 3x2 contingency table with the three phenotypic categories versus two genotypic categories, that is, the non-risk genotype (TT) and the combined risk genotypes (TC and CC).
Results::
No statistically significant differences were observed. The p-value for the 3x2 two-tailed exact test was p=.83.
Conclusions::
Based on this study the CFH polymorphism is not a significant factor in determining the individual phenotype resulting from the RDS IVS 2+3 A→T mutation. However, due to the small sample size, subtle effects may have been missed. Therefore we are currently expanding the number of samples to increase the power of the study.
Keywords: gene modifiers • retinal degenerations: hereditary • genetics