Abstract
Purpose: :
Genome Wide Association Studies (GWAS) have enabled identification of genetic associations for many complex traits. Myopia and refractive error are highly heritable. We conducted a GWAS of refractive error in an unselected volunteer cohort of British Caucasian adult twins.
Methods: :
Non-cycloplegic autorefraction was obtained for volunteers from the TwinsUK Adult Twin Registry attending our institution. Mean spherical equivalent for both eyes was used calculated from the standard formula: spherical equivalent= sphere + (cyl/2) in twins. All individuals included subsequently underwent genotyping with Human Hap 300k Duo for part of the cohort, and Human Hap610 Quad array for the rest (platforms from Illumina, San Diego, CA). Association analysis was performed using Merlin (http://www.sph.umich.edu/csg/abecasis/merlin/).
Results: :
4388 subjects (315 males and 3,955 females) with a mean age of 55 years (SD 12) were included in this study. The mean spherical equivalent was -0.4 (SD 2.73) diopters (D), range -25.12 to +9.4 D. 286,481 SNPs fulfilled quality control criteria (Hardy-Weinberg equilibrium p>0.001, minor allele frequency of at least 0.04, genotyping success rate for the SNP at least 95%) and were included in analysis. Several genetic variants on chromosome 15 were associated with refractive error to high levels of statistical significance, each explaining around 1% of variance, and will be presented, with replication cohorts.
Conclusions: :
It seems likely that there are multiple genetic variants, each of small effect size, associated with refractive error, similar to other complex traits. This means large-scale meta-analyses will be required to establish the genetic basis of the high heritability of this trait.
Keywords: myopia • genetics • gene microarray