HLA-G is a tolerogenic molecule that expresses in cytotrophoblast cells and plays an important role in immune response suppression in maternal decidua. Interactions between the extracellular domains of the HLA-G protein with cell receptors of the immune system are well-known.This study investigated the association between HLA-G gene polymorphism with repeated implantation failure (RIF). We used PCR followed by the sequencing technique for exons 2, 3, and 4, as well as intron 2 of the HLA-G gene in 100 couples with histories of two or more failed assisted reproductive technique (ART) attempts. The data were compared with the results of our previous study.The results indicated that some alleles of the HLA-G gene such as: 0106, 010106, 01010106 and 0105N (null) alleles were significantly higher in the patient group compared to the control group (p<0.05). There were higher SNPs at the +482 T/C and +506 -/C positions in failed ART couples compared to controls (p=0.03; p=0.01, respectively).HLA-G gene polymorphisms do not clearly affect the risk for implantation failure in most couples who undergo ART. However allelic variations, particularly in exons 3 and 4, and intron 2 of the HLA-G gene can lead to ART failure in human embryos.
Keywords: ART; HLA-G polymorphism; Implantation; RIF.