RESUMO
<p><b>OBJECTIVE</b>To investigate the association between IL-18 polymorphisms and the risk of unexplained recurrent spontaneous abortion (URSA).</p><p><b>METHODS</b>The polymorphism of rs187238, rs360718 and rs360717 in IL-18 was determined by PCR in combination with DNA sequencing in 207 patients with URSA and 144 women with normal pregnancy.</p><p><b>RESULTS</b>The frequency of gene types GG, GC+CC of rs187238 (-137 G/C) in URSA group and control group was 77.3%, 22.7%, and 95.8%, 4.2%, respectively (χ²=22.767, P<0.001). The frequency of allele C in URSA group was significantly higher than that in control groups (13.04% vs 2.1%, χ²=26.102, P<0.001) . The risk of spontaneous abortion in C allele carriers was 7.050 times higher than that in G allele carriers (OR=7.050, 95%CI: 2.990-16.622). No significant difference in genotype frequency and allele frequency of rs360718 and rs360717 polymorphism was noticed between URSA group and control group (χ²=1.497, P=0.221; χ²=0.858, P=0.354).</p><p><b>CONCLUSION</b>GC+CC genotype and C allele of Rs187238 in IL-18 gene are associated with the susceptibility of recurrent spontaneous miscarriage. Rs360718 and rs360717 in IL-18 may not be associated with URSA.</p>