Objective: To investigate the association between the functional polymorphisms of Foxp3 gene and unexplained recurrent spontaneous abortion (URSA).
Methods: PCR-restriction fragment length polymorphism (rs3761548, rs2294021) and PCR with sequence-specific primers (rs2232365, rs5902434) were used to detect four polymorphisms of Foxp3 in 146 URSA cases and 112 normal controls.
Results: (1) The frequencies of rs3761548A/C were 10.3%, 22.3% in genotype C/C, 38.4%, 40.2% in genotype A/C and 51.4%, 37.5% in genotype A/A between URSA patients and normal controls; the frequencies of rs2232365A/G were 5.5%, 15.2% in genotype A/A, 47.9%, 50.0% in genotype A/G, 46.6%, 34.8% in genotype G/G between URSA patients and normal controls; they all reached statistical difference (P < 0.05). The carriers of rs3761548A allele and rs2232365G allele increased the risk of URSA (OR = 1.73, 1.61;all P < 0.05). (2) There was no difference in the genotypic distribution of rs5902434del/ATT polymorphism between cases and controls (P = 0.10), but the frequency of del allele in URSA was statistically increased than that of controls (71.2%, 62.5%;OR = 1.49, P = 0.04). (3) There was no different distribution in 3 genotypes (C/C, T/C, T/T) and 2 alleles (T and C) of rs2294021T/C between URSA patients and normal controls (P = 0.18 and 0.08). (4) Estimated haplotype frequency distribution of rs5902434del/ATT, rs3761548A/C and rs22323565A/G showed haplotype del-A-G conferring the susceptibility to URSA (OR = 2.51, P < 0.01) but haplotype del-C-G and ATT-A-A could provide protection on URSA (OR = 0.18, 0.22; all P < 0.01).
Conclusion: Functional polymorphisms of Foxp3 gene could probably confer the susceptibility to URSA, by altering Foxp3 function and (or) its expression.