DUPLICATION 20P IDENTIFIED VIA FLUORESCENT IN-SITU HYBRIDIZATION

A 3-year-old girl is reported with dup (20p) resulting from 3:1 segreg ation of a de novo t(20;21). The proposita presented with minor anomal ies, developmental delay a clinical phenotype suggestive of 20p trisom y, and a karyotype with a 21p+ and an additional small marker chromoso me. Conventional cytogenetic techniques were not informative for the i dentification of the origin of the extra material of chromosome 21p no r for the marker chromosome. The 21p+ and marker chromosomes were succ essfully characterized using fluorescent in situ hybridization (FISH). (C) 1994 Wiley-Liss, Inc.