Common variants on chromosome 2 and risk of primary open-angle glaucoma in the Afro-Caribbean population of Barbados

Primary open-angle glaucoma (POAG) is the second leading cause of blindness worldwide. Although a number of genetic loci have shown association or genetic linkage to monogenic forms of POAG, the identified genes and loci do not appear to have a major role in the common POAG phenotype. We seek to identify genetic loci that appear to be major risk factors for POAG in the Afro-Caribbean population of Barbados, West Indies. We performed linkage analyses in 146 multiplex families ascertained through the Barbados Family Study of Glaucoma (BFSG) and identified a strong linkage signal on chromosome 2p (logarithm of odds score = 6.64 at theta = 0 with marker D2S2156). We subsequently performed case-control analyses using unrelated affected individuals and unaffected controls. A set of SNPs on chromosome 2p was evaluated in two independent groups of BFSG participants, a discovery group (130 POAG cases, 65 controls) and a replication group (122 POAG cases, 65 controls), and a strong association was identified with POAG and rs12994401 in both groups (P < 3.34 E-09 and P < 1.21E-12, respectively). The associated SNPs form a common disease haplotype. In summary, we have identified a locus with a major impact on susceptibility to the common POAG phenotype in an Afro-Caribbean population in Barbados. Our approach illustrates the merit of using an isolated population enriched with common disease variants as an efficient method to identify genetic underpinning of POAG.