Characterization of a rare short arm heteromorphism of chromosome 22 in a girl with down-syndrome like facies

Abdelhafid Natiq, Siham Chafai Elalaoui, Thomas Liehr, Saïd Amzazi, Abdelaziz SefianiIndian Journal of Human Genetics 2014 20(1):89-91Chromosomal 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.
Source: Indian Journal of Human Genetics - Category: Genetics & Stem Cells Authors: Source Type: research