Abstract
Purpose :
Age-related macular degeneration (ARMD) has a significant genetic influence. The Armenian ethnogenesis is considered a genetically isolated population, and the Armenian genocide created a genetic bottleneck. Therefore, we hypothesized that the genetic involvement of ARMD in Armenians is different than that of other Caucasian/European populations. To our knowledge, this is the first reported evaluation of the genetic contribution of AMRD susceptibility genes in an Armenian population.
Methods :
We genotyped 224 Armenian subjects living in the Glendale, California, area for 13 genes and their corresponding SNPs (ABCA1, APOE, ARMS2, C2, C3, CETP, CFB, CFH, CFI, COL8A1, LIPC, TIMP3) to assess the relationship of these SNPs in AMD affecting people of Armenian heritage. We calculated allele frequencies of the SNPs using all subjects and compared them to the frequencies in the Caucasian population from the 1000 Genomes Project as well as 20,000 Caucasian controls from our database. We performed an analysis on our Armenian subjects to identify differences in distribution of risk alleles (CFH and ARMS2), the average number of risk alleles, and age in Armenian vs. Caucasian population. We utilized Chi-squared and Mann Whitney analyses to check for statistical significance. IRB approval was obtained.
Results :
Overall, the SNPs show a high level of similarity in allele frequency (CFH and ARMS2) and distribution of alleles to the Caucasian population and controls. However, a statistical difference was evident in age where Armenian patients with AMD were about five years older on average than Caucasian patients, controlling for stage of AMD. The association analysis showed two SNPs (both in the complement factor H gene) and the indel (in the Age-Related Maculopathy Susceptibility 2 gene) are significantly associated with AMD (p<0.01; Bonferroni adjusted p<0.05/5 genes).
Conclusions :
There were no statistical differences between Armenian and Caucasian populations in the frequency or distribution of the CFH and ARMS2 risk alleles. However, there was a statistical difference in age between Armenians versus Caucasians where Armenian patients were on average about five years older than Caucasians. Additional analysis must be conducted with a larger sample size to fully demonstrate the associations between the Armenian population and the European population and to understand the genes that are associated with a higher incidence of AMD.
This is a 2020 ARVO Annual Meeting abstract.