Association of OCT derived drusen measurements with AMD associated-genotypic SNPs in Amish population

To investigate the association of OCT derived drusen measures in Amish age-related macular degeneration (AMD) patients with known loci for macular degeneration.

Members of the Old Order Amish community in Pennsylvania ages 50 and older were assessed for drusen area, volume and regions of retinal pigment epithelium (RPE) atrophy using a Cirrus High- Definition-OCT. Measurements were obtained in the macula region within a central circle (CC) of 3 mm diameter and a surrounding perifoveal ring (PR) of 3 to 5 mm diameter using the Cirrus OCT RPE analysis software. Other demographic information including age, gender and smoking status were collected. Study subjects were further genotyped to determine their risk for the AMD associated SNPs in SYN3, LIPC, ARMS2, C3, CFB, CETP, CFI and CFH genes using TaqMan genotyping assays. The association of genotypes with OCT measures were assessed using linear trend p-values calculated from univariate and multivariate generalized linear models.

432 eyes were included in the analysis. Multivariate analysis (adjusted by age, gender and smoking status) confirmed the known significant association between AMD and macular drusen with the number of CFH risk alleles for drusen area (area increased 0.12 mm² for a risk allele increase, p<0.01), drusen volume (volume increased 0.01 mm³ for a risk allele increase, p≤0.05) and area of RPE atrophy (area increased 0.43 mm² for a risk allele increase, p=0.003). SYN3 risk allele G is significantly associated with larger area PR (area increased 0.09 mm² for a risk allele increase, p=0.03) and larger drusen volume in central circle (volume increased 0.01 mm³ for a risk allele increase, p=0.04).

Among the genotyped SNPs tested, the CFH risk genotype appears to play a major role in determining the drusen phenotype in the Amish AMD population.