Twin pregnancy with complete hydatidiform mole (46,XX) and fetus (46,XY): Genetic origin proved by analysis of chromosome polymorphisms

Abstract

Hydatidiform mole may be separated into two entities on the basis of histopathology, cytogenetics, and biochemical markers. Complete moles lack the presence of a fetus, are almost always female, and are androgenetic in origin. In contrast, partial moles have a range of villi from normal to hydatidiform, focal rather than conspicuous hyperplasia, and evidence of the presence of a fetus. When karyotype analysis of the placenta and fetus has been carried out partial moles have generally been found to be triploid. Cases of mole with coexistent fetus must now be assessed in the light of these findings. In a case of complete hydatidiform mole with fetus the genetic origins were defined by the use of chromosomal polymorphisms. The fetus had a normal 46,XY karyotype with evidence of the presence of both maternal and paternal chromosomes. The mole was 46,XX and of androgenetic origin. There was no evidence of a maternal contribution, and duplication of paternal chromosomes was shown. In such atypical molar pregnancies examining genetic polymorphisms yields much more information than do sex chromosome studies and karyotyping, particularly in confirming the diagnosis and defining the origin and aetiology of the condition.