Prenatal detection of Turner's syndrome in conjunction with trisomy 20 mosaicism (45,X/46, X, +0).

A case of Turner's syndrome, detected antenatally and complicated by the finding of trisomy 20 mosaicism in 50% of cells from each of two amniotic fluid cultures, is described. Cultures from seven fetal tissues in the subsequent abortus showed a predominance of 45,X cells, but nevertheless suggested the existence of a very low level of trisomy 20 mosaicism in three fetal tissues. The diagnostic dilemma in interpreting trisomy 20 mosaicism is discussed.