Evaluation of LOXL1 polymorphisms in primary open-angle glaucoma in southern and northern Chinese

PURPOSE: The lysyl oxidase-like protein 1 (LOXL1) gene is strongly associated with exfoliation glaucoma, which is very rare in the Chinese population. The implicated LOXL1 polymorphisms have not been associated with primary open-angle glaucoma (POAG). In this study, we investigated three of the LOXL1 polymorphisms in POAG in a southern Chinese population of Hong Kong and northern Chinese from Beijing. METHODS: The Hong Kong group included 293 POAG patients and 250 controls, and the Beijing group included 169 POAG patients and 197 controls. LOXL1 single nucleotide polymorphisms (SNPs), rs1048661, rs3825942, and rs2165241, were genotyped by direct DNA sequencing. Individual association was analyzed using the χ(2) test, and haplotype-based association analysis was performed in WHAP. RESULTS: Each of the candidate SNPs was not statistically associated with POAG in either group (p>0.017, Bonferroni correction). Haplotype-based association analysis had identified a significant omnibus association (Omnibus χ(2)=18.16, p=0.00115) between these SNPs and POAG in the Hong Kong group. A minor haplotype (T-G-T) showed significant statistical association with POAG. It presented in 2.1% of cases and 0.4% of controls, conferring a 5.24 fold of increased risk to the disease (95% CI: 1.17–23.54, P(perm)=0.00108). However, this haplotype was absent in the Beijing group. CONCLUSIONS: Individual LOXL1 SNPs, rs1048661, rs3825942, and rs2165241, were not associated with POAG in the Chinese population. However, a minor haplotype T-G-T was found to be associated with the disorder in the southern Chinese. The low frequencies of the at-risk alleles at rs1048661 and rs2165241 may be one of the factors that led to the low prevalence of exfoliation syndrome in the general populations of the Chinese.