title: Mosaic hexasomy 21.
abstract: Cases in which there are more than three copies of a sex chromosome, and rarely of an autosome, have been reported, but to our knowledge hexasomy has never been described except in tissue undergoing neoplastic change. This report describes a female infant with multiple malformations in whom we found a mosaic hexasomy 21. This was first detected in amniotic fluid cells and subsequently in skin fibroblasts.
mesh_terms: D000015:Abnormalities, Multiple / Q000235:genetics*; D000653:Amniotic Fluid / Q000166:cytology; D000782:Aneuploidy; D002478:Cells, Cultured; D002904:Chromosomes, Human, 21-22 and Y; D005260:Female; D005347:Fibroblasts / Q000648:ultrastructure; D006801:Humans; D007231:Infant, Newborn; D009030:Mosaicism