The Association between Copy Number Variations in GlutathioneS-transferase M1 and T1 and Age-Related Cataract in a Han Chinese Population

Abstract

To determine the contribution of copy number variation (CNV) in glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) to the susceptibility to age-related cataract (ARC) and its subtypes in a Han Chinese population. ARC cases (n = 279) and controls (n = 145) were included from a Han Chinese population-based prospective study. Quantitative RT-PCR and the DeltaCt method were used to determine the presence of no, one, or multiple alleles of GSTM1 and GSTT1. The RNaseP gene was used as the internal control. The GSTT1 null genotype was associated with ARC with an odds ratio (OR) of 1.56 (P < 0.05). Deletion of at least one GSTT1 allele also influenced the onset of ARC (OR = 2.16, P < 0.01). Consistent associations were observed between GSTT1 CNV and cortical cataract. The deletion of at least one GSTT1 allele was associated with an OR of 4.81 for developing cortical ARC (P < 0.001), although individuals who had more than two copies of GSTT1 had a reduced risk of cortical ARC (OR = 0.19, P < 0.05). The frequency of the GSTT1 null genotype in the Han Chinese population differed dramatically from that in Caucasians. No association was detected between GSTM1 CNV and ARC. An association was observed between GSTT1 CNV and ARC in a Han Chinese population. The GSTT1 CNV is most closely associated with cortical cataract risk. The loss of at least one GSTT1 allele increases the risk of cortical cataract, whereas gain in GSTT1 copy number reduces the risk.