Gestational Trophoblastic Disease - Etiology

Etiology

Hydatidiform moles are abnormal conceptions with excessive placental development. Conception takes place, but placental tissue grows very fast, rather than supporting the growth of a fetus.

Complete hydatidiform moles have no fetal tissue and no maternal DNA. A single sperm duplicates and this duplicated sperm fertilises an empty ovum, or, two sperms fertilise an empty ovum (dispermic fertilisation). An empty ovum is a maternal egg which has no functional maternal DNA.

Partial hydatidiform moles have a fetus or fetal cells. They are triploid in origin, i.e. one set of maternal haploid genes and two sets of paternal haploid genes. They almost always occur following dispermic fertilisation of a normal ovum (fertilisation of one egg by two sperm).

Malignant forms of GTD are very rare. About 50% of malignant forms of GTD develop from a hydatidiform mole.