Polymorphisms in the FOXP3 gene in Han Chinese psoriasis patients

Background: Psoriasis is a common dermatological disorder, in which autoimmunity plays an important role. CD4(+)CD25(+) regulatory T cells (T-regs) have been suggested to be involved in the pathogenesis of some autoimmune diseases. T-regs express the fork head/winged helix transcription factor, FOXP3, which appears to be of key importance in the development and function of T-regs. Studies have found that single-nucleotide polymorphisms (SNPs) in the FOXP3 gene contribute to susceptibility to some autoimmune disorders. However, information about FOXP3 gene in psoriasis is limited.

Objective: This study evaluated the association between FOXP3 gene SNPs and susceptibility to psoriasis in a Han Chinese population.

Methods: In a hospital-based case-control study, 524 patients with psoriasis and 549 psoriasis-free controls were recruited according to age and gender. We investigated four SNPs in the FOXP3 gene (-6054, deletion/ATT; -3279, A/C; -924, A/G; IVS9+459, A/G) in psoriatic patients, and assessed allele and genotype frequencies in psoriatic patients (237 females, 287 males) and normal controls (272 females, 277 males). The polymorphisms were genotyped using the PCR sequence-specific primer (PCR-SSP) technique and PCR-restriction fragment length polymorphism (RFLP) analysis.

Results: We found that increased risk of psoriasis was associated with the FOXP3 -3279 AC genotype (adjusted OR, 1.32; 95% CI, 1.01-1.74) and the combined AC+AA genotype (adjusted OR, 1.38; 95% CI, 1.07-1.78), compared with the -3279 CC genotype. We also found that an increased risk of psoriasis was associated with the FOXP3 IVS9+459 GG genotype (adjusted OR, 2.24; 95% CI, 1.41-3.58). However, the combined GA+GG genotype showed no such tendency (adjusted OR=1.28; 95% CI, 1.00-1.64), compared with the IVS9+459 AA genotype. There was no evidence of an increased risk associated with the FOXP3-6054 deletion/ATT or FOXP3-924 A/G genotype. In combined genotype analyses, the FOXP3-3279 AC+AA genotype was more obviously associated in males (adjusted OR=1.60, 95% CI=1.11-2.31) and severe psoriasis patients (PASI score >20; adjusted OR=1.97, 95% CI=1.41-2.75). Meanwhile, the FOXP3 IVS9+459 GA+GG genotype was also associated with severe psoriasis patients (adjusted OR=1.69, 95% CI=1.21-2.36).

Conclusions: FOXP3 polymorphisms appear to contribute to the risk of psoriasis in a Han Chinese population. Larger studies are needed to confirm these findings.