Prenatal diagnosis of a trisomy 7/trisomy 13 mosaicism

Double aneuploidy mosaicism of two different aneuploidy cell lines is a rare event [1]. The most frequently described combinations are a monosomy X cell line with a cell line containing a trisomy of an autosome. In literature, mosaicism of a monosomy X cell line with either a trisomy 7, 8, 10, 13, 18 or 21 have been reported [2-7]. Double autosomal trisomies are even more sporadic, and to date combinations of trisomies of the chromosomes 8 and 14, chromosomes 8 and 21, chromosomes 13 and 18, chromosomes 13 and 21, and chromosomes 18 and 21 have been reported [1,8-12].Here, we present the first report of a double trisomy mosaicism involving chromosomes 7 and 13 in both amniotic fluid and subsequent FISH analysis of fibroblasts in a fetus presenting with multiple congenital anomalies.A 17-year-old healthy woman of a non-consanguineous couple, gravida 1, para 0, was referred at 21+0 weeks' gestation because of multiple structural anomalies. There was no history of familial congenital anomalies or drug use. The pregnancy was unplanned but welcome. A dating scan had been performed at 8 weeks' gestation. A 12 weeks' scan was not performed since the parents did not wish screening for Down syndrome. The fetus showed growth restriction with a large bilateral cleft lip and palate with severe micrognathia. The caput showed mild brachycephaly, with an enlarged cisterna magna (> p95). The left little finger was bowed and there were mild clubfeet. Following genetic counselling the patient elected to have an amniocentesis for karyotyping. Moreover, the parents requested a termination of pregnancy.Labour was induced at 22+2 weeks and a female baby was born, who died shortly after birth. Her birth weight was 370 g. Autopsy confirmed the bilateral cleft lip and palate as well as the retrognathia, and revealed an internal malrotation of the digestive tract with the ileocecal valve situated in the upper abdomen on the left side and bicornate uterus. All body and organ measures were wit