An Investigation Into LOXL1 Variants in Black South African Individuals With Exfoliation Syndrome

Objective: To investigate the association between 2 lysyl oxidase-like 1 (LOXL1) polymorphisms, rs1048661 (R141L) and rs3825942 (G153D), and exfoliation syndrome (XFS) in black South African individuals. Methods: A total of 43 black patients with XFS and 47 ethnically matched controls were recruited for genetic analysis. Samples were analyzed for presence of the LOXL1-R141L and G153D variants using restriction fragment length polymorphism analysis. A case-control association study was performed. Results: The R141L and G153D single-nucleotide polymorphisms (SNPs) were both significantly associated with XFS (P = .00582 and P < .00001, respectively). Consistent with findings in white populations but not in Asian cohorts, the GG genotype of the R141L SNP was present in significantly more XFS cases than controls (P = .00582). However, in this black South African study population, the AA genotype of G153D was present in an overwhelming majority of cases with XFS (P < .00001; odds ratio, 17.10; 95% confidence interval, 4.91-59.56), contrary to all previous articles in which the GG genotype was strongly associated with the disease phenotype. Conclusion: The LOXL1 SNPs R141L and G153D are significantly associated with XFS in this black South African population. The AA genotype of G153D confers XFS risk in this population, as opposed to the GG genotype described in all other populations, suggesting that unidentified genetic or environmental factors independent of these LOXL1 SNPs may influence phenotypic expression of the syndrome.