Lack of evidence for a role of HLA-DP in unexplained recurrent spontaneous abortion

Relationship between HLA-DPA1 genetic polymorphism and anembryonic pregnancy

BACKGROUND

Human leukocyte antigen (HLA)-DP is an HLA class II molecule. Overexpression of HLA class II molecules in placental trophoblast cells may induce pregnancy loss. However, the association between HLA-DP and pregnancy loss remains unclear. HLA-DPA1 is an HLA-DP peptide chain. The objective of this study was to assess the association between HLA-DPA1 genetic polymorphism and anembryonic pregnancy, a type of early pregnancy loss, in the Chinese population.

METHODS

A case-control study was designed to compare the frequencies of HLA-DPA1 gene polymorphisms in an anembryonic pregnancy group and a control group. Sixty-eight cases and 122 controls were recruited. Statistical analysis was performed to assess the correlation between single-nucleotide polymorphisms (SNPs) and anembryonic pregnancy susceptibility. MassARRAY high-throughput DNA analysis was used to analyze 19 HLA-DPA1 SNPs. To explore how HLA-DPA1 polymorphism could affect anembryonic pregnancy, HLA-DPA1 serum levels were analyzed by ELISA.

RESULTS

Homozygous typing of rs1431403 (CC and TT) significantly increased the risk of anembryonic pregnancy in the case group (ORCC  = 3.13, 95% CI: 1.50-6.53; ORTT  = 2.96, 95% CI: 1.31-6.66; ORCC+TT  = 3.06, 95% CI: 1.62-5.78). In samples with high HLA-DPA1 levels (≥1,500 pg/ml), the homozygous rs1431403 genotypes (nCC  = 21, 43.8%; nTT  = 20, 57.1%) were observed more frequently than were heterozygous genotypes.

CONCLUSION

HLA-DPA1 rs1431403 may be a risk factor for anembryonic pregnancy in the Chinese population. Homozygous rs1431403 genotypes (CC and TT) may increase the risk of anembryonic pregnancy by aberrantly increasing the HLA-DPA1 levels.

Maternal HLA-DR, HLA-DQ, and HLA-DP loci are linked with altered risk of recurrent pregnancy loss in Lebanese women: A case-control study

PROBLEM

We investigated the association between idiopathic recurrent pregnancy loss (RPL) and HLA-DPB1, HLA-DQB1, and HLA-DRB1 alleles and DPB1-DQB1-DRB1 haplotypes.

METHOD OF STUDY

Case-control retrospective study involved 93 Lebanese women with unexplained RPL, and 113 multiparous Lebanese women with two or more successful pregnancies, and no miscarriages who served as controls. DPB1, DQB1, and DRB1 genotyping was performed by PCR-SSP.

RESULTS

Expected and observed DRB1, DQB1, and DPB1 frequencies were comparable, and HLA genotype frequencies were in Hardy-Weinberg equilibrium. Significantly higher frequencies of DRB1*04:01:01 and DRB1*08:01:01, and decreased DRB1*07:01:01 frequency were seen in RPL cases than in controls. On the other hand, the distribution of DQB1 alleles was comparable between cases and control groups. Significantly lower frequencies of DPB1*04:01:01 and DPB1*14:01:01 were seen in women with RPL than control subjects. While the frequency DPB1*02:01:01 was markedly higher in RPL cases than in controls, the difference was not significant. DPB1-DQB1-DRB1 haplotype analysis identified haplotype DPB1*04:01:01-DQB1*03:02:01-DRB1*04:01:01 to be positively associated, while haplotype DPB1*04:01:01-DQB1*02:01:01-DRB1*07:01:01 to be negatively associated with RPL. Of these two haplotypes, only DPB1*04:01:01-DQB1*02:01:01-DRB1*07:01:01 remained significant after correction for multiple tests (P_c  = .0008).

CONCLUSION

Our results confirm an association of select DRB1 and DPB1 alleles with RPL in Lebanese women, and the first to identify DPB1-DQB1-DRB1 linked with altered RPL susceptibility, further highlighting the immunological/inflammatory nature of RPL.