[Importance of trisomy-20 mosaicism to prenatal diagnosis (author's transl)].

Trisomy-20 mosaicism was among the findings obtained from two prenatal diagnoses and is discussed in this paper. The pregnant women concerned decided to ask for termination of pregnancy. Eight instances of prenatally diagnosed trisomy-20 mosaicism and three cases of pseudomosaicism so far have been reported elsewhere in the literature. Six pregnancies were carried to full term, with phenotypically normal infants being delivered. Hence, prenatal diagnosis of trisomy-20 mosaicism alone does not seem to justify termination of pregnancy. Yet, abandonment of termination should be flanked by follow-up checks of the children delivered, in order to rule out subsequent manifestation of mental defects.