Involvement of genes encoding apoptosis regulatory factors (FAS, FASL, TRAIL, BCL2, TNFR1 and TNFR2) in the pathogenesis of autoimmune thyroid diseases

Apoptosis is necessary for the maintenance of self-tolerance by eliminating autoreactive immune cells in the periphery. To clarify the association between the pathogenesis of autoimmune thyroid disease (AITD) and genes encoding apoptosis regulatory factors, we genotyped the FAS −1377G/A, −670A/G, FASL −844C/T, TRAIL −716C/T, BCL2 −938C/A, +127G/A, TNFR1 −383A/C and TNFR2 +676T/G polymorphisms. The frequencies of the FASL −844CC and BCL2 −938AA genotypes were significantly lower in AITD patients than in control subjects (P = 0.0101 and 0.0307, respectively). The frequency of the TNFR2 +676TT genotype was significantly lower in Graves' disease (GD) patients than in controls (P = 0.0284). The serum sFasL level was significantly higher in GD and Hashimoto's disease (HD) patients than in control subjects (P = 0.0003 and 0.0017, respectively). The serum sFasL levels in control subjects were significantly lower than those in intractable GD, GD in remission, and HD without treatment (P = 0.0310, 0.0007 and 0.0002, respectively). The serum sFasL levels in HD with treatment were significantly lower than those in HD without treatment (P = 0.0490). The polymorphisms in genes encoding apoptosis regulatory factors (FASL, BCL2) and serum levels of sFasL may be associated with immune dysregulation.