PRENATAL-DIAGNOSIS AND CLINICAL FINDINGS IN A CASE OF HEXASOMY-12P

We report the first case of hexasomy 12p mosaicism due to 2 copies of an apparent i(12p) [46,XX/48,XX,+i(12p),+i(12p)]. In every cell that c ontained the i(12p), 2 copies of the marker were found. The hexasomy w as found in amniocytes (16%) and skin fibroblasts (95%) but not in per ipheral blood lymphocytes. The chromosomal origin of the marker was co nfirmed with the use of in situ hybridization of alpha-satellite speci fic for the centromere of chromosome 12. The present case was diagnose d following chromosome analysis for anomalies on ultrasound. The hexas omy 12p patient showed striking phenotypic similarities with severely affected tetrasomy 12p cases and died shortly after birth. We propose that the more severe presentation of this case is due to the 4 extra c opies of 12p. (C) 1993 Wiley-Liss, Inc.