HL-A haplotypes and unexplained infertility

Mode of inheritance of HLA haplotypes locus A,B in siblings of different sexes

METHOD

Forty-eight parents and 172 children were typed for class I HLA antigens, locus A,B.

RESULTS

Although the number of cases is small, we observed: (1) a significantly decreased number of sons born after a first delivery of a son, as compared to a first delivery of a daughter; (2) significantly increased sharing of maternal class I HLA antigens between the firstborn son and his brothers from higher birth orders, as compared to his sisters; and (3) HLA-A2 antigen, which is known to be involved in HLA restricted cytotoxic reactions in the recognition of minor histocompatibility antigens, was inherited in subsequent deliveries of sons as compared to daughters in a significantly higher frequency from the paternal than from maternal HLA haplotype. The results suggest that sharing of identical maternal HLA haplotypes between brothers may aid to decrease the degree of maternal sensitization to fetal antigens, and lack of HLA-2 antigen in maternal cells from sons as compared to daughters may avoid maternal HLA-A2 restricted cytotoxic reactions toward the male fetus.

HLA-A,B compatibility in parents of offspring with neural-tube defects or couples experiencing involuntary fetal wastage

To test the contribution of a putative human analogue of the murine T locus to neural-tube defects (N.T.D.) and involuntary fetal wastage, HLA-A, B compatibility between husband and wife was studied in a group of 77 couples with known obstetric histories. The frequency of sharing of HLA-A,B antigens was significantly higher in 13 couples with recurrent fetal loss at one gestational age and in 11 couples whose offspring had had a lethal N.T.D. than in 17 couples with three or more normal pregnancies. The extent of HLA compatibility--that is, the number of antigens shared by husbands and wives--was significantly higher in 16 couples with one spontaneous abortion, 23 couples with recurrent spontaneous abortions, and 21 couples with N.T.D. offspring than in controls. These data are consistent with a contribution of a locus in or near the HLA complex to N.T.D. and involuntary fetal wastage.