Problem and method: 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.
Results: 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.
Conclusions: The results suggest that extended MHC haplotypes, disadvantageous for reproduction, exist in some isolated populations, such as the Finns.