Lack of an association of apolipoprotein E gene polymorphisms with familial age-related macular degeneration

Background: Previously, the ε4 allele of apolipoprotein E (APOE) was reported to have a significant association with a decreased risk of age-related macular degeneration (AMD). In addition, the ε2 allele of APOE was reported to be possibly associated with an increased risk of AMD. Objective: To determine if APOE polymorphisms, previously reported to be associated with AMD, affect its expression in medium to large families, as well as in unrelated patients with AMD. Methods: The APOE genotype was determined by HhaI restriction digests of polymerase chain reaction-amplified products in a collection of 259 affected and 207 unaffected individuals from 56 AMD families. Genotypes were determined similarly in a set of 104 unrelated AMD patients and in 113 unaffected control subjects. Diagnosis of AMD was based on clinical examination and evaluation of fundus photographs. Evidence of an association between alleles of APOE and AMD in families was tested by the following 4 statistical methods: χ² analysis of simple allele counting, logistic regression analysis adjusting for age, construction of likelihood ratios of haplotype frequencies, and the pedigree disequilibrium test. Results: None of the statistical methods used showed a significant association between the common alleles of APOE and AMD in our collection of families or in the set of unrelated AMD patients. Conclusions: No evidence was found to support an association between AMD in medium to large families and the ε4 or ε2 alleles of APOE. Neither was any evidence found for an association of APOE polymorphisms with the set of unrelated patients with AMD. However, a trend for a decreased risk of AMD associated with APOE ε4 was observed in the set of unrelated patients with a family history of AMD.