LOXL1 polymorphisms and APOE genotypes in pseudoexfoliation syndrome and pseudoexfoliation glaucoma in Turkish population

Pseudoexfoliation syndrome (XFS) is the most common identifiable cause of open-angle glaucoma worldwide. Three common sequence variants in the lysyl-oxidase like 1 gene (LOXL1) were found to be associated with pseudoexfoliation glaucoma (XFG) and XFS in various populations. Apolipoprotein E (APOE) genotypes were found to be associated with XFS in Turkish population in a previous study but these results were not repeated in other populations. In this study we investigate whether single nucleotide polymorphisms (SNPs) in the LOXL1 gene and genotypes of APOE gene are associated with XFS and XFG in the Turkish population. This case-control study comprised of 80 unrelated patients withXFS (including 40 patients with XFG) and 80 control subjects. Genotyping of LOXL1 SNPs (rs1048661, rs3825942 and rs2165241) and APOE was done by restriction fragment length polymorphism (RFLP) method. Statistical analysis was done by SPSS 11.5 (Statistical Package for Social Science) Allele and genotype frequencies of the intronic SNP rs2165241 and one of the exonic SNP rs3825942 were found to be significantly associated with XFS and XFG individually. The T allele of rs2165241 (OR [95%CI]:6.83 [4.2-11.2]) and the G of rs3825942 (OR [95%CI]: 13.6 [4.1-45.4]) were risk alleles for XFS. But after adjusting for rs3825942, rs2165241 no longer remained significant (p:0.081). The other exonic SNP rs1048661 were not found to associated with XFS in our study population (p: 0.623). In the haplotype analysis T-G-T and G-G- T were found to be risk haplotypes (OR [95%CI]: 10.6 [2.4-46.5]) and OR [95%CI]:4.1 [2.6-6.6] respectively). No significant differences of allelic and genotypic frequencies of LOXL1 SNPs were found between patients with XFS without glaucoma and XFG. We found no significant association between allele and genotype frequencies of APOE and XFS and XFG (p>0.05). The intronic SNP rs2165241 and out of the two non-synonymous SNPs in exon 1 of the LOXL1 gene; rs3825942 have a significant association with XFS cases in Turkish population. The risk alleles and genotypes have a similar pattern with Caucasian and not with the Asians. In contrast with the previous study in Turkish population our data showed that APOE genotypes are not associated with XFS and XFG in Turkish population.