Background: It seems that 50% of the possible causes of recurrent miscarriage do not have any explainable etiology and they require in-depth etiopathogenesis analysis. The purpose of this research was to study polymorphisms relationship of the im-mune response genes including Val249Ile CX3CR1 (rs3732379), CT60 G/A CTLA4 (rs3087243), and HLA DQA1, DQB1, DRB1 (major histocompatibility complex, class II) with development of idiopathic form of recurrent miscarriage (iRM) in Kazakh population. Methods: TagMan genotyping for 302 patients with iRM and 300 women with normal reproduction was performed. Molecular genetic studies were carried out by the TaqMan method of unified site-specific amplification and real-time genotyping using test systems. Statistical tests and Chi Square were carried out using PLINK, STATA13 software and p˂0.05 was considered statistically significant. Results: It has been shown that carriage of unfavorable genotypes (Val/Ile, Val/Val) by the Val249Ile polymorphism of CX3CR1 gene increases the risk of developing iRM by 1.43 times. Search for associations of genes allelic variants of HLA class 2 complex with iRM revealed 501 allele in DQA1 locus, 0301 in DQB1 locus, 10, 12, 15, 16 alleles in DRB1 locus, which increase the risk of developing iRM in Kazakh population. Conclusion: The highly significant associations of immune response genes with development of iRM in Kazakh population indicate the possible involvement of the immune system interaction of mother cells with syncytiotrophoblast, which is realized by vascular defects and defective embryo implantation, causing termination of pregnancy.

There are numerous scientific studies of recurrent miscarriage (RM) with possible causes, such as fetal chromosomal abnormalities, infectious agents, adverse environmental factors, bad habits, anatomical defects, thrombophilic disorders, etc. However, RM causes in 50% of cases remain unknown. These RM cases do not have any explainable etiology, and they require in-depth etiopathogenesis study, thus they are considered idiopathic RM. The purpose of this research is to study polymorphisms relationship of the immune response genes CX3CR1 (rs3732379, Val249Ile), CTLA4 (rs3087243, CT60 G/A), and HLA DQA1, DQB1, DRB1 (major histocompatibility complex, class II) with the idiopathic form of recurrent miscarriage (iRM) development in Kazakh population. Independent replicative TagMan genotyping for 302 patients with iRM and 300 women with normal reproduction was performed. It has been shown that carriage of unfavorable genotypes (Val/Ile, Val/Val) by the Val249Ile polymorphism of the CX3CR1 gene increases the risk of developing iRM by 1.43 times. Search for associations of genes allelic variants of HLA class 2 complex with iRM revealed *501 allele in DQA1 locus, *0301 in DQB1 locus, *10, *12, *15, *16 alleles in DRB1 locus, which increases the risk of developing iRM in Kazakh population with OR from 1.34 to 4.5. As a result of the study, obtained highly significant associations of immune response genes with the development of iRM in the Kazakh population indicate the possible involvement of the immune system interaction of mother cells with syncytiotrophoblast, which is realized by vascularization defects, defective embryo implantation, and leads to early pregnancies’ termination.