Two non-familial extra supernumerary abnormal chromosomes (ESAC) were detected in fetuses monitored by midtrimes ter amniocentesis. Characterization of these ESACs was carried out using conventional cytogenetic analysis, fluorescence in situ hybridization, and DNAse I hypersensitivity. Based on these studies it was concluded that the two ESACs were derived respectively from chromosomes 14/22 and isodicentric chromosome 15. Based on cytogenetic results it was argued that unconsistent phenotypic effect was associated with the two aneuploidies. This optimistic view was confirmed at birth of unaffected babies and unremarkable follow up at 6 and 12 months.