Genetic mapping of a maternal locus responsible for familial hydatidiform

Hydatidiform mole (HM) is the product of an aberrant human pregnancy in which there is an abnormal embry-onic development and proliferation of placental villi. The incidence of HM varies between ethnic groups, and oc-curs in 1 in every 1500 pregnancies in the USA. All HM cases are sporadic, except for extremely rare familial cases. The exact mechanisms leading to molar preg-nancies are unknown. We previously postulated that women with recurrent hydatidiform moles are homozy-gous for an autosomal recessive defective gene. To map this gene genetically, we initiated a genome-wide scan with highly polymorphic short tandem repeats in individ-uals from two families with recurrent HM. Here, we dem-onstrate that a defective maternal gene is responsible for recurrent HM. This gene resides on chromosome 19q13.3–13.4 in a 15.2 cM interval flanked by D19S924 and D19S890. The identification of a gene for HM adds new insights into the molecular genetics of early em-bryogenesis and may be relevant to the large number of patients with sporadic HM