Fetal HLA-G alleles and their effect on miscarriage

Immunosuppression at the feto-maternal interface is crucial for a successful pregnancy outcome. Human leukocyte antigen-G (HLA-G) seems to be a major contributor to fetal tolerance. The HLA-G expression is seen in cytotrophoblasts and in maternal blood. Fetal HLA-G acts on decidual antigen-presenting cells (APCs), natural killers (NKs) and T cells. Recent findings revealed that defects in placentation and their consequences are associated with maternal HLA-G variants and their expression levels. The objective of this article is to investigate the relationship between fetal HLA-G alleles and miscarriage, which has not been investigated to date. The present study includes 204 recurrent miscarriage (RM) cases who were admitted to our clinic between 2012 and 2016. Twenty-eight miscarriage products without maternal cell contamination and any known pathology were analyzed by HLA-G typing. In addition, 3' untranslated region (UTR) 14-base pair (bp) insertion/deletion polymorphism was also investigated by Sanger sequencing. For our population, the most frequent HLA-G type was G*01:01, both in the study group (30.3%) and in the control group (47%). The study revealed that the G*01:04 allele was significantly associated with miscarriage (p = 0.007). The 3' UTR 14bp deletion was more frequent in the miscarriage group, but there was no significant correlation. HLA-G alleles seem to be related with miscarriage and should be considered in RM cases.