HLA-G is a class I major histocompatibility complex gene that is expressed in cytotrophoblasts at the materno-fetal interface. It has been suggested that HLA-G could play a key role in materno-fetal immunological interactions during pregnancy. To investigate whether there is an association between HLA-G locus and recurrent spontaneous miscarriage, HLA-G alleles were determined by a PCR-RFLP method in 38 couples with recurrent spontaneous miscarriage and in 26 random control couples. In this series parental HLA-G sharing, extended HLA-G/A haplotypes and the frequencies of the HLA-G alleles were similar in the two groups. Thus, our data suggest that there is no detectable relation between susceptibility to recurrent spontaneous miscarriage and HLA-G locus.
The role of major histocompatibility complex (MHC) genes in the etiology of recurrent spontaneous abortion (RSA) was studied by analyzing the polymorphism of several, at least 14, immunogenetically important MHC genes either by serological or molecular methods in 56 Finnish RSA couples, and in 29 infants born to these families during the follow-up period of two years after the abortions.
The haplotype analysis showed that the RSA couples had significantly increased sharing of MHC fragments, compared to the control families. Furthermore, the MHC risk markers for abortions defined 12 different, extended MHC haplotypes that were found in a significantly higher proportion among persons in the RSA group (45%) than in the controls (11%). However, neither of these observations associated with the reproductive success of the study couples.
The results suggest that extended MHC haplotypes, disadvantageous for reproduction, exist in some isolated populations, such as the Finns.