The genetics of gestational trophoblastic disease: a rare complication of pregnancy.

Gestational choriocarcinoma is usually a rapidly spreading fatal disease, but it is curable if diagnosed early and treated. It is a unique malignancy that is a partial or complete allograft with a genotype that is not the same as the host genotype. It is most often preceded by an abnormal molar pregnancy. The surprising and unique androgenetic origin of complete hydatidiform molar pregnancies was first revealed by Kajii and Ohama in 1977. We describe the current understanding of the morphology, epidemiology and genetics of gestational trophoblastic disease that followed the milestone findings by Kajii and Ohama.