Evaluation of KIR gene expression in patients with recurrent implantation failure

Abstract

Infertility affects one out of ten reproductive age couples globally, while in Romania one out of six couples is reported to seek infertility counsel. The success of reproduction is highly dependent on maternal-fetal immune interaction. The balance between all activator and inhibitor signals between uterine natural killer (uNK) cells and the trophoblast represents a key factor and may influence embryo implantation. Uterine natural killer cells express surface receptors (KIR) which, after recognition of class I HLA molecules expressed by the trophoblast, may stimulate or inhibit the ability of uNK cells to produce soluble factors and may present a low toxicity required to maintain the embryo and allogeneic fetus. We aimed to prove that the investigation of the genetic background of uNK receptors represented by KIR genotyping may be a useful tool in the assessment of recurrent implantation failure (RIF), may help predict therapy outcome, and clarify disease pathogenesis. This is a prospective study conducted on 96 RIF patients and 80 fertile controls. We aimed to investigate whether the presence or absence of each gene or KIR genotype is correlated to the implantation success or to first-trimester miscarriage. The study results point out that the AA inhibitor genotype is associated with weak results in terms of achieving pregnancy following in vitro fertilization (IVF), and the presence or absence of certain genes is correlated to the success of implantation and to first-trimester miscarriage.