Evaluation of LOXL1 polymorphisms in eyes with exfoliation glaucoma in Japanese

PURPOSE To investigate the lysyl oxidase-like 1 (LOXL1) gene for single nucleotide polymorphism (SNP) variations in Japanese patients with exfoliation syndrome (XFS) and exfoliation glaucoma (XFG) and to examine the phenotypes of the patients with these variations. METHODS Fifty-six unrelated Japanese patients with XFS, including 36 patients with XFG, were studied. Genomic DNA was extracted from the leukocytes of peripheral blood, and three SNPs (rs1048661; p.Arg141Leu, rs3825942; p.Gly153Asp, and rs2165241) were identified. These SNPs were amplified by polymerase chain reaction (PCR), directly sequenced, and genotyped. RESULTS Two nonsynonymous variants in exon 1 of LOXL1,rs1048661 and rs3825942, were found to be strongly associated with XFS including XFG. The frequency of the T allele (0.964) in rs1048661 in eyes with XFS was much higher in controls (0.507) with a p value of 7.7x10(-18). The odds ratio for the T allele in rs1048661 was 26.0 (95% confidence interval, 18.3-37.1). In the haplotype analysis, T-G was overrepresented in XFS subjects (p=7.7x10(-18)), showing a highly significant difference in frequency between primary open-angle glaucoma (POAG) and the control group (p=0.07), but the G-G and G-A haplotypes were less represented in XFS subjects (p=1.1x10(-11) and p=1.0x10(-4), respectively). However, an earlier study reported the strongest associated SNP with XFS and XFG, rs2165241, showed no association. CONCLUSIONS SNPs of LOXL1 (rs1048661; Arg141Leu and rs3825942; Gly153Asp) are highly associated with XFS in the Japanese population. However, unidentified genetic or environmental factors independent of LOXL1 will most likely influence the phenotypic expression of the syndrome.