Associations of the G1961E and D2177N variants in ABCA4 and the risk of age-related macular degeneration

Objective: The aim of this study was to identify the relationship between G1961E and D2177N variants in the ABCA4 gene with AMD susceptibility. Design and methods: All eligible studies published up to October 2014 were obtained from MEDLINE, EMBASE, and ISI Web of Science. The pooled odds ratio (OR) with 95% confidence intervals (CIs) was calculated to evaluate the strength of this association. Results: Twenty-four studies enrolling 4580 AMD cases and 5180 controls were identified. Both G1961E (OR. = 3.22, 95% CI: 1.74-5.95) and D2177N (OR. = 2.36, 95% CI: 1.41-3.93) variations showed significant associations with increased risk of AMD. In addition, a more significant relationship in the D2177N mutation with increased risk for AMD was found in Americans (OR. = 4.31, 95% CI: 1.90-9.73), while no association was demonstrated in Europeans. For Asians, no carriers of the risk factor A allele in either variant were detected in any of AMD patients and control subjects. Conclusions: Significant evidence was found for a relationship between the G1961E and D2177N variants in ABCA4 with increased susceptibility to AMD, specifically for Americans. However, large-scale studies are still required to further validate these findings in different ethnicities.