Normal outcome of a pregnancy with mosaicism for double trisomy in amniotic fluid cells

True chromosomal mosaicism of double trisomy (48,XX, +7, +20) was detected in amniotic fluid cell cultures at 16 and 20 weeks of gestation. No aneuploid cells were found in chorionic villus samples (CVS) by semidirect preparation and long-term culture. High-level ultrasound did not indicate any structural abnormality of the fetus. At 38 weeks of gestation, a phenotypically normal girl was born. She is now 22 months old and normally developed. At birth, various samples were investigated by routine cytogenetic methods or by fluorescence in situ hybridization with the probe p7t1 (umbilical cord blood, placental tissue, umbilical cord fibroblasts, urine sediment) and no abnormal cells could be detected in any of those tissues.