Diagnosis of chromosomal anomalies due to adjacent-1 malsegregation resulting from translocation heterozygotes.

Patients who are carriers of reciprocal translocations may have pregnancies with unbalanced karyotypes that result in miscarriage or congenital anomalies of offspring. We report 3 cases of unbalanced karyotype resulting from adjacent-1 malsegregation in the conceptuses of heterozygous carriers of balanced translocations. The combined use of genetic markers in ultrasound, chromosomal analysis and fluorescence in situ hybridization to make accurate prenatal diagnosis is described.