Prenatal diagnosis of fetal trisomy 6 mosaicism and phenotype of the affected newborn.

The first case of a fetal trisomy 6 mosaicism proven at 25 weeks of gestation by analysis of fetal urine cells is described. Chromosomal analysis was indicated by an ultrasonographically diagnosed heart defect at 21 weeks of gestation. The chromosomal aberration was detected in amniotic fluid cells while fetal blood cells showed a normal chromosome set. At term a boy with normal growth parameter was born. In addition to the expected heart defect, malformations of hands and feet were present.