Prenatal diagnosis of trisomy 20 mosaicism indicating esophageal and rectal origin

Abstract
Trisomy 20 mosacism in cultured amniotic fluid cells in only a few cases was confirmed in fetal tissue. This may lead to the assumption that the trisomic cells are of extra-fetal origin and interruption of the pregnancy is not advisable. Chromosome analysis of numerous fetal tissues indicated in 2 cases the presence of 1 or more trisomy 20 cell clones in rectum and esophagus, respecively. The clinical significance in trisomy 20 mosaicism in single organs remains to be elucidated. Besides the karyotype, genetic counseling should take into account all accessible information of the pregnancy, e.g., ultrasound, serum .alpha.-fetoprotein values and obstetrical history.