Reply to Liu et al.: Differential effects of chromosome 2p16.3 variants on glaucoma in African derived populations

Abstract

We appreciate the letter by Liu et al. (1) and commend them on their work (1). We are encouraged that they have confirmed association of primary open-angle glaucoma (POAG) with rs12994401, although it is to the opposite allele from that seen in the Barbados population (2). These results, in addition to the presence of a monogenic POAG locus in this region, provide substantive confirmation of a locus for POAG (3). The inverse association of risk alleles between African Americans is not completely surprising given the high degree of genetic diversity in African and African-derived populations (4) and previously described divergent levels and patterns of linkage disequilibrium (LD) in African subpopulations (5). The situation becomes even more complex when migration patterns to the Caribbean islands are considered (6). We agree with the conclusion by Liu et al. (1) that rs12994401 most likely represents a tagging SNP that is in linkage disequilibrium with a yet unidentified causative SNP in this region.