title: Characterization of a rare short arm heteromorphism of chromosome 22 in a girl with down-syndrome like facies.
abstract: Chromosomal heteromorphisms are described as interindividual variation of chromosomes without phenotypic consequence. Chromosomal polymorphisms detected include most regions of heterochromatin of chromosomes 1, 9, 16 and Y and the short arms of all acrocentric chromosomes. Here, we report a girl with Down-syndrome such as facies and tremendously enlarged short arm of a chromosome 22. Fluorescence in situ hybridization (FISH) with a probe specific for all acrocentric short arms revealed that the enlargement p arms of the chromosome 22 in question contained exclusively heterochromatic material derived from an acrocentric short arm. Parental studies identified a maternal origin of this heteromorphism. Cryptic trisomy 21 of the Down-syndrome critical region was excluded by a corresponding FISH-probe. Here, we report, to the best of our knowledge, largest ever seen chromosome 22 short arm, being ~×1.5 larger than the normal long arm.
authors: Department of Medical Genetics, National Institute of Health, Morocco, Africa ; Department of Medical Genetics, Faculty of Sciences of Rabat, University Mohamed V Agdal, Morocco, Africa.
authors: Abdelhafid
authors: A
authors: Natiq
authors: Department of Medical Genetics, National Institute of Health, Morocco, Africa ; Human Genomic Center, University Mohamed V Souissi, Rabat, Morocco, Africa.
authors: Siham Chafai
authors: SC
authors: Elalaoui
authors: Department of Medical Genetics, University of Jena, Institute for Humangenetics, D-07740 Jena, Germany.
authors: Thomas
authors: T
authors: Liehr
authors: Department of Medical Genetics, Faculty of Sciences of Rabat, University Mohamed V Agdal, Morocco, Africa.
authors: Saïd
authors: S
authors: Amzazi
authors: Department of Medical Genetics, National Institute of Health, Morocco, Africa ; Human Genomic Center, University Mohamed V Souissi, Rabat, Morocco, Africa.
authors: Abdelaziz
authors: A
authors: Sefiani
keywords: Acrocentric p arms; fluorescence in situ hybridization; heteromorphism; karyotype