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J. A. Peet, S. Baek, L. Tian, J. Shults, E. Pugh, M. F. Cotch, D. Stambolian; Age-Related Macular Degeneration (AMD) in the Old Order Amish: Prevalence and Impact of Y402H Variant. Invest. Ophthalmol. Vis. Sci. 2009;50(13):271.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the prevalence of AMD and impact of the Y402H variant in an Old Order Amish (OOA) population-based sample.
Fifteen hundred thirty-one OOA participants (mean age, 63.5 years) from 558 families were recruited in the Lancaster County, Pennsylvania area. Participants received complete eye exams and provided blood samples for DNA analysis. Digital fundus photographs taken through dilated pupils were graded by an independent center using the Wisconsin age-related maculopathy grading system. An AREDS grade ≥ 3 in either eye was considered affected for AMD. DNA was genotyped for the Y402H gene variant (rs1061170) of the complement factor H gene. Logistic regression, generalized estimating equation (GEE), quasi-least squares (QLS), and mixed effect (ME) models were used.
The overall prevalence of AMD in this cohort is 21.3%, (65.2% among the 46 people aged 85+). The Y402H variant was found to be in Hardy-Weinberg equilibrium with an allelic frequency of 48.0%. Among males, 22.7% were CC homozygotes (19.6% aged 75+) compared to 23.9% (26.5% aged 75+) of females. After adjusting for age, Y402H allele status, and an age-gender interaction, results from the logistic, GEE and QLS models indicate that males had more than a six-fold higher risk of AMD compared to females. Heterozygotes (CT) for the Y402H gene variant were not statistically more likely to have AMD compared to TT homozygotes. The odds of AMD for CC homozygotes relative to those with at least one T allele were 1.6 (95% CI 1.2-2.2) in all models. Familial correlation coefficients ranged from 0.07 to 0.12.
The prevalence of AMD in the OOA is higher than other Caucasian populations of comparable age. Among the 228 OOA aged 75+, 40% with at least one T allele and 60% of CC homozygotes had AMD. The gender differential in CC homozygosity among the oldest members in this cohort is intriguing.
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