Association of Polymorphisms at the SIX1/SIX6 Locus With Normal Tension Glaucoma in a Korean Population

We demonstrated that SIX1/SIX6 locus polymorphism (rs10483727 and rs33912345) was significantly associated with a genetic susceptibility to NTG in a Korean population. More studies are needed to investigate whether the SIX1/SIX6 locus is associated with NTG among various ethnic populations.

Several previous studies have reported that the relevance of the SIX1/SIX6 locus to open angle glaucoma (OAG) in various ethnic populations. However, definitions of OAG patients were different among those studies. The relevance of the SIX1/SIX6 locus to normal tension glaucoma (NTG) in a Korean population remains uncertain. Therefore, the purpose of this study was to investigate the relationship of the SIX1/SIX6 locus with NTG in a Korean cohort.

Patients with NTG and ethnically matched healthy controls were recruited from eye clinics in Korea (210 cases and 117 controls). Four polymorphisms (rs33912345, rs12436579, rs2179970, and rs10483727) of the SIX1/SIX6 locus were genotyped for 327 subjects using a TaqMan single nucleotide polymorphism genotyping assay.

The rs33912345 polymorphism was significantly correlated with NTG in the recessive model [odds ratio (OR): 0.265; 95% confidence interval (CI): 0.078-0.898, P =0.033], but not in the allelic and dominant models (both P >0.05). The SNP rs10483727 was significantly associated with NTG in the allelic model (OR: 0.674; 95% CI: 0.464-0.979, P =0.038) and the recessive model (OR: 0.187; 95% CI: 0.058-0.602, P =0.005). Genetic association analysis of SNP rs12436579 and rs2179970 revealed no significant difference in genotype distribution between NTG cases and controls in the allelic, dominant, or recessive models (all P >0.05).

The current study found that SIX1-SIX6 locus rs10483727 and rs33912345 polymorphisms were significantly associated with NTG risk in the Korean population.