Association of IGF1 gene haplotypes with high myopia in Chinese adults.

OBJECTIVE To investigate the association of high myopia with common single-nucleotide polymorphisms (SNPs) in the IGF1, IGFBP3, and IGFBP4 genes in a Chinese population. METHODS For our case-control study, we recruited 600 unrelated participants: 300 case participants with high myopia (-8.00 diopters or less) and 300 emmetropic controls (within ±1.00 diopter). Twenty-one tag SNPs were selected from these candidate genes and were genotyped. Genotype data were analyzed by logistic regression. Multiple comparisons were corrected by running 15 000 permutations of case-control status. RESULTS Although we did not find any significant association for IGF1 SNPs using single-marker analysis, we identified many windows with haplotype frequencies significantly different between case participants and control participants using a variable-sized sliding-window strategy. In particular, the most significant association was shown by a 3-SNP window consisting of rs12423791, rs7956547, and rs5742632 (omnibus test: asymptotic P(asym) = 3.70 × 10(-9) and empirical P(emp) = 6.67 × 10(-5)). There were 3 high-risk haplotypes: CAC (P(asym) = 2.35 × 10(-6); odds ratio [OR], 5.06), GAT (P(asym) = 3.56 × 10(-4); OR, 3.18), and GGC (P(asym) = 2.25 × 10(-3); OR, 25.10). There was 1 protective haplotype: GAC (P(asym) = 8.43 × 10(-4); OR, 0.63). On the other hand, our single-marker and haplotype analyses did not show any significant association for IGFBP3 and IGFBP4. CONCLUSIONS IGF1 haplotypes are associated with genetic susceptibility to high myopia in Chinese adults, whereas IGFBP3 and IGFBP4 are unlikely to be important in the genetic predisposition to high myopia. CLINICAL RELEVANCE IGF1 is associated with high myopia, and identifying the causal variants is important for understanding the underlying mechanisms.