TAP1 I333V gene polymorphism and type 1 diabetes mellitus: a meta-analysis of 2248 cases.

Transporter associated with antigen processing 1 (TAP1) I333V gene polymorphism has been suggested to be associated with type 1 diabetes mellitus (T1DM) susceptibility. However, the results from individual studies are inconsistent. To explore the association of TAP1 I333V gene polymorphisms with T1DM, a meta-analysis involving 2246 cases from 13 individual studies was conducted. The pooled odd ratios (ORs) and their corresponding 95% confidence intervals (95% CIs) were evaluated by a fixed-effect model. A significant relationship was observed between TAP1 I333V gene polymorphism and T1DM in allelic (OR: 1.35, 95% CI: 1.08-1.68, P = 0.007), dominant (OR: 1.462, 95% CI: 1.094-1.955, P = 0.010), homozygous (OR: 1.725, 95% CI: 1.082-2.752, P = 0.022), heterozygous (OR: 1.430, 95% CI: 1.048-1.951, P = 0.024) and additive (OR: 1.348, 95% CI: 1.084-1.676, P = 0.007) genetic models. No significant association between TAP1 I333V gene polymorphism and T1DM was detected in a recessive genetic model (OR: 1.384, 95% CI: 0.743-2.579, P = 0.306) in the entire population, especially among Caucasians. No significant association between them was found in an Asian or African population. TAP1 I333V gene polymorphism was significantly associated with increased T1DM risk. V allele carriers might be predisposed to T1DM susceptibility.