GENETIC-ORIGIN OF MALIGNANT TROPHOBLASTIC NEOPLASMS

The genetic origin of three trophobIastic neoplasms [two choriocarcino mas and a placental site trophoblast tumor (PSTT)] was determined by a nalysis of the restriction fragment length polymorphism (RFLP) pattern . One choriocarcinoma, which was believed not illogically to have deve loped from an antecedent complete mole, contained both paternal and ma terial RFLP alleles and thus was probably the product of a normal fert ilization. The other choriocarcinoma was not of gestational origin but had RFLPs homozygous at some loci and heterozygous at others, compati ble with the parthenogenic origin of this tumor from a germ cell after meiosis I. The PSTT required amplification of DNA sequences by polyme rase chain reaction (PCR) because of the small amount of tumor materia l available. This tumor contained RFLP alleles from both parents and a ppeared to have resulted from a previous unrecognized (and abnormal) p regnancy.