Background. HLA-G molecules exhibit immunomodulatory properties that can delay graft rejection. The 14？bp insertion/deletion polymorphism (INDEL) (rs16375) influences the stability of final HLA-G mRNA and its soluble isoforms. Objective. The present study aimed to investigate the possible association between this polymorphism and the incidence of acute rejection in Iranian liver transplant recipients. Methods. Different genotypes were evaluated by PCR. The patients who had acute rejection within 6 months after transplantation were classified as acute rejection (AR) group, while others were considered as nonacute rejection (NAR) group. Results. Among the recipients, 21 patients (21%) had at least one episode of AR, while the other 79 patients (79%) had normal liver function. No significant differences were found between the two groups regarding sex, MELD score, and primary liver disease. Also, no difference was observed concerning rs16375 genotype and allele frequency ( , OR: 0.69; CI: 0.21–2.10). Conclusion. The study results revealed no significant difference between the AR and the NAR groups regarding the 14？bp INDEL genotypes and alleles. Further studies are recommended to be conducted on other polymorphic sites as well as monitoring of serum HLA-G concentration in order to ascertain the potential implications of this marker in our population. 1. Introduction The human leukocyte antigen-G (HLA-G) belongs to the major histocompatibility complex (MHC) located on the short arm of chromosome 6. During HLA-G gene transcription, 7 different isoforms are produced, four of which are membrane bound (HLA-G1 through HLA-G4) and three are soluble (HLA-G5 through HLA-G7) [1–3]. HLA-G is predominantly expressed at the maternal-fetal interface and plays an important role in fetal-maternal tolerance which is the perfect example of a semiallograft [4]. HLA-G protects the fetus against the immunological damage caused by maternal natural killer and T-cytotoxic cells (CTLs) during pregnancy [5]. In nonpathological conditions, expression of HLA-G is detected in thymus, cornea, proximal nail matrix, pancreas, and hematopoietic stem cells. There is strong evidence that HLA-G expression is associated with the reduced incidence of acute and chronic rejection in solid organ transplantation [2, 3]. HLA-G is involved in graft acceptance following human allotransplantation, such as heart, lung, liver, and kidney [6–8]. The endomyocardial cells in the heart, biliary epithelial cells of the liver, and the tubular epithelial cells in the kidney are the important targets of the
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