MOLECULAR CHARACTERIZATION OF 2 EXTRA MARKER CHROMOSOMES DETECTED AT PRENATAL-DIAGNOSIS

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