MAJOR HISTOCOMPATIBILITY COMPLEX LOCATED COMPLEMENT C4 AND STEROID 21-HYDROXYLASE GENE REARRANGEMENTS IN COUPLES WITH RECURRENT SPONTANEOUS ABORTIONS

Major histocompatibility complex class II and III in Addison's disease. MHC alleles do not predict autoantibody specificity and 21-hydroxylase gene polymorphism has no independent role in disease susceptibility

The major autoantigens in Addison's disease have recently been shown to be members of the adrenal steroidogenic enzymes, such as 21OH. The genes encoding the 21OH enzyme are located in the class III segment of the MHC complex. Therefore, its identification as an autoantigen provides a novel link between MHC and susceptibility to this autoimmune disease. We have determined the MHC class II (DRB1, DQA1, DQB1, DPB1) and class III (TNF, HSP70, C4, 21OH) gene polymorphism in patients with Addison's disease. Also, we tested whether presence of autoantibodies against 21OH is associated with specific alleles in MHC. Our results show that patients with Addison's disease in association with APS2 or Addison's disease as an isolated form share highly similar MHC class II and class III alleles. A very strong association with HLA DRB1*0301, DQA1*0501, DQB1*0201, and DPB1*0101, as well as with the C4A + 21OHA gene deletion and TNFB*1 allele was observed. However, identical gene markers were observed also in controls matched for DRB1*0301, thus suggesting that the patient group did not carry MHC gene segments specific for Addison's disease. The presence of autoantibodies against 21OH was not found to be directly determined by the MHC alleles; rather it was associated with the clinical form of the disease.

A set of MHC haplotypes found among Finnish couples suffering from recurrent spontaneous abortions

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.