Analysis of single nucleotide polymorphisms at 13 loci within the transforming growth factor-induced factor gene shows no association with high myopia in Japanese subjects.

A previous study in China first indicated that the transforming growth factor-induced factor (TGIF) is a probable candidate gene for high myopia. The purpose of our study was to investigate whether there are significant associations between high myopia and single nucleotide polymorphism (SNP) variants in the TGIF gene of Japanese subjects. Genomic DNA was collected from 330 Japanese subjects with high myopia and at a level refractive error was less than -9.25 Dsph and 330 randomized controls without high myopia. Thirteen SNPs were detected by polymerase chain reaction (PCR) and primer extension or by PCR and SNP-specific fluorogenic probes in all of the cases and controls. Thirteen SNPs were found within the TGIF genes of the cases and controls. Two of the SNPs were monomorphic and none of the 13 SNPs showed a significant result. The pairwise linkage disequilibrium (LD) mapping confirmed that these alleles have a comparatively strong LD index of >0.8 for D' and >0.4 for r(2). We found no statistical association between any of the 13 SNPs located on the TGIF gene and high myopia in Japanese subjects. Based on our study using Japanese subjects and the previous studies of TGIF gene polymorphism in Chinese and northern European subjects with myopia, there is no convincing evidence to prove a connection between nucleotide sequence variations in TGIF and high myopia.