Genetic association of insulin-like growth factor-1 polymorphisms with high-grade myopia in an international family cohort.

PURPOSE Evidence from human myopia genetic mapping studies (MYP3 locus), modulated animal models, and observations of glycemic control in humans suggests that insulin-like growth factor (IGF)-1 plays a role in the control of eye growth. This study was conducted to determine whether IGF-1 polymorphisms are associated with myopia in a large, international dataset of Caucasian high-grade myopia pedigrees. METHODS Two hundred sixty-five multiplex families with 1391 subjects participated in the study. IGF-1 genotyping was performed with 13 selected tag single nucleotide polymorphisms (SNPs) using allelic discrimination assays. A family-based pedigree disequilibrium test (PDT) was performed to test for association. Myopia status was defined using sphere (SPH) or spherical equivalent (SE), and analyses assessed the association of (1) high-grade myopia (<or=-5.00 D), and (2) any myopia (<or=-0.50 D) with IGF-1 markers. Results were declared significant at P<or=0.0038 after Bonferroni correction. Q values that take into account multiple testing were also obtained. RESULTS In all, three SNPs-rs10860860, rs2946834, and rs6214-were present at P<0.05. SNP rs6214 showed positive association with both the high-grade- and any-myopia groups (P=2x10(-3) and P=2x10(-3), respectively) after correction for multiple testing. CONCLUSIONS The study supports a genetic association between IGF-1 and high-grade myopia. These findings are in line with recent evidence in an experimental myopia model showing that IGF-1 promotes ocular growth and axial myopia. IGF-1 may be a myopia candidate gene for further investigation.