Abstract
Purpose:
The exact nature of the genetic mechanisms underlying ocular growth in myopia has not been fully established. A number of factors have been implicated through animal studies, in particular, the early growth response protein Egr-1 in mice (Zenk, the avian homolog of Egr-1 in chicks). In Egr-1 knockout mice, several other differentially expressed genes; pcdhb9, narf, ogdh and selenbp1 have also been identified. We wished to assess the association of these genes in common myopia, refraction, axial length, anterior chamber depth and corneal curvature in an Australian cohort.
Methods:
Individuals of European background were recruited as part of the Genes in Myopia (GEM) Study. Myopia was defined as -0.5D or less in the right eye. A total of 543 individuals from the GEM study were used for analysis including 314 myopic and 229 non myopic individuals. Tag single nucleotide polymorphisms (SNPs) were chosen to encompass 2kb upstream of the start codon through to 2kb downstream of the stop codon of the chosen genes. Statistical analysis used logistic and linear regression methods including age and sex as covariates. Bonferroni corrections were applied to account for multiple testing.
Results:
28 SNPs were genotyped encompassing the EGR-1, PCDHB9, NARF, OGDH AND SELENBP1 genes. Following statistical analysis and correction for multiple testing (corrected p=0.05/28=0.0018), association at SNP rs17133935 in the OGDH gene remained statistically significant for corneal curvature (p uncorrected=0.0008).
Conclusions:
A variant in the OGDH gene was shown to be associated with corneal curvature in this cohort. The ERG-1, PCDHB9, NARF, OGDH AND SELENBP1 genes did not appear to be associated with myopia, refractive error, anterior chamber depth and axial length in this cohort. This is the first report of OGDH, a gene involved in the tricarboxylic acid cycle, being associated with corneal curvature suggesting there may be a potential mitochondrial involvement in this phenotype.
Keywords: 605 myopia •
539 genetics