Myocilin polymorphisms and high myopia in subjects of European origin

Three previous studies have tested for an association between high myopia and polymorphisms in the open angle glaucoma gene, myocilin (MYOC), all in subjects of Chinese ethnicity. In two of the studies, a significant association was found while in the third, there was no association. We sought to investigate the association between high myopia and polymorphisms in MYOC in subjects of European ethnicity.

Subjects were recruited from two sites, Cardiff University in the UK and Duke University in the United States. The Cardiff University cohort was comprised of 164 families with high myopia (604 subjects) plus 112 unrelated, highly myopic cases and 114 emmetropic controls. The Duke University cohort was comprised of 87 families with high myopia (362 subjects) plus 59 unrelated, highly myopic cases. Subject DNA was genotyped with a panel of MYOC single nucleotide polymorphisms (SNPs) including those found previously associated with high myopia. The Cardiff cohort was also genotyped for two flanking microsatellite markers analyzed in prior studies. Association between high myopia and MYOC polymorphisms was assessed using the Unphased program.

Since there was no evidence of heterogeneity in genotype frequencies between families and singleton samples or between cohorts, both subject groups (families and unrelated subjects) from both recruitment sites were analyzed jointly for those SNPs genotyped in common. Two variants showed significant association before correction for multiple testing. These two variants were rs16864720 (p=0.043) and NGA17 (p=0.026). However, there was no significant association after Bonferroni correction. The estimated relative risk (RR) conferred by each of the MYOC variants was low (RR<1.5).

Our results suggest that MYOC polymorphisms have a very low, or possibly negligible, influence on high myopia susceptibility in subjects of European ethnicity.