De novo chromosomal aberrations in the fetus; genetic counseling and clinical outcome.

The aim of this study was to examine the incidence and clinical outcome of de novo chromosomal aberrations retrospectively and provide useful data for genetic counseling in the prenatal cytogenetic diagnosis. We found 17 cases of de novo chromosomal aberrations in 5501 cases of prenatal cytogenetic analysis and reviewed the karyotype, further study, medical records, fetal ultrasound findings and clinical outcomes. Out of the 17 de novo chromosomal aberrations, 5 had balanced reciprocal translocations and 12 had unbalanced translocations characterized as deletion, addition, or marker. In the case of the five balanced reciprocal translocations, 3 cases without abnormal ultrasound findings were carried to term after comprehensive genetic counseling. Neonates were phenotypically normal and clinical examinations were normal. Two cases with abnormal ultrasound findings were terminated therapeutically. Twelve cases of unbalanced translocations were terminated except one case with a mosaic marker chromosome. High resolution fetal ultrasound and detailed cytogenetic and molecular study will be adjunctive tools for predicting the karyotype/phenotype correlations of fetuses with de novo chromosomal aberrations, although they have limitation to find all phenotypic effects.