Human lymphocyte antigen expression in hydatidiform mole: androgenesis following fertilization by a haploid sperm.

Thirteen hydatidiform moles (complete moles) and lymphocytes from each parent were analyzed for human lymphocyte antigen (HLA-A and HLA-B specificities). It was demonstrated that molar tissues expressed homozygous A and B specificities which were identical to those of the father and not those of the mother. It was concluded that androgenesis was responsible for the pathogenesis of most cases of complete mole. There was homozygous expression of paternal HLA specificities which were heterozygous for A locus and/or B locus in eight of nine cases of complete mole. This suggests that these hydatidiform moles developed from an egg which was fertilized by a haploid sperm which duplicated its own chromosomes after meiosis.