Genetic Association of the PARL-ABCC5-HTR3D-HTR3C Locus With Primary Angle-Closure Glaucoma in Chinese

Purpose: This study evaluates the associations of haplotype-tagging single nucleotide polymorphisms (SNPs) in the PARL-ABCC5-HTR3D-HTR3C region with primary angle closure glaucoma (PACG), with a view to identify the responsible SNP in this region. Methods: Thirty SNPs from the PARL-ABCC5-HTR3D-HTR3C region were genotyped in a Hong Kong Chinese cohort of 422 PACG patients and 400 control subjects, using TaqMan SNP genotyping assays. Single marker and haplotype-based association analyses were performed. Results: Two synonymous ABCC5 SNPs, namely rs939336 (p.Cys594=; P = 0.013; odds ratio OR = 1.46; 95% confidence interval CI, 1.08 to 1.97) and rs1132776 (p.Ala395=; P = 0.009; OR = 1.47; 95% CI: 1.10 to 1.95), were associated with PACG. Mild associations were detected for ABCC5 rs9838667 (P = 0.024) and HTR3D rs12493550 (P = 0.035). Conditional analysis revealed that no SNPs remained significant after adjusting for other SNPs, suggesting none of these tagging SNPs is fully responsible for the association in this region. In subgroup analysis, ABCC5 SNPs rs939336, rs1132776, and rs983667 and HTR3D rs12493550 were associated only with the chronic form of PACG. However, these associations could not withstand the correction for multiple testing. Conclusions: These findings enrich the allelic spectrum of ABCC5 in PACG. We identified no tagging SNP responsible for the association of the whole region. Further deep sequencing analysis of this region should be warranted to uncover whether there is still disease associated variant in this region.