Purpose  To investigate the association of common variants in or near CDC7/TGFBR3, ZP4, SRBD1, ELOVL5, CAV1/CAV2, TLR4, CDKN2B, CDKN2B-AS1, ATOH7, PLXDC2, TMTC2, SIX1 and CARD10, previously reported to be associated with glaucoma in the literature, with primary open angle glaucoma (POAG) in the Afro-Caribbean population of Barbados.

Methods  A total of 440 unrelated subjects were recruited for this study, including 274 with POAG and 166 unaffected individuals. Eighteen SNPs were genotyped by using the multiplex SNaPshot method. Allelic, genotypic and model-based (dominant, recessive and additive) associations of the SNPs with POAG were analyzed by Chi-squared test and logistic regression.

Results  SNP rs1063192 is significantly associated with POAG (allelic P=0.0008, genotypic P=0.0029). The minor allele C of rs1063192 was protective against POAG (OR = 0.39; 95%CI = 0.22-0.69). Suggestive association was seen with rs7916697 (allelic P = 0.0096, genotypic P = 0.01) with the minor allele also being protective (OR = 0.67; 95% CI = 0.50-0.91), although this did not withstand correction for multiple testing. However, a significant interactive effect on POAG risk was identified between rs1063192 and rs7916697 (P-interaction = 2.80 x 10-5). Individuals with rs1063192 protective genotype CC or CT and also rs7916697 genotypes GG or GA have a significantly decreased risk of POAG (OR=0.17, 95%CI: 0.07-0.41).

Conclusions  Our study confirmed a significant association between SNP rs1063192 (CDKN2B, previously shown to influence vertical cup-to-disc ratio) at 9p21 and POAG in the Afro-Caribbean population of Barbados. The minor allele of rs1063192 acts interactively with that of rs7916697 (ATOH7) to reduce POAG risk. Our results also suggest that rs1063192 is a common protective variant for POAG in populations of both European descent and African descent.