Characterization of a rare short arm heteromorphism of chromosome 22 in a girl with down-syndrome like facies
Abdelhafid Natiq1, Siham Chafai Elalaoui2, Thomas Liehr3, Saïd Amzazi4, Abdelaziz Sefiani2
1 Department of Medical Genetics, National Institute of Health; Faculty of Sciences of Rabat, University Mohamed V Agdal, Morocco, Africa, 2 Department of Medical Genetics, National Institute of Health; Human Genomic Center, University Mohamed V Souissi, Rabat, Morocco, Africa, 3 Department of Medical Genetics, University of Jena, Institute for Humangenetics, D-07740 Jena, Germany, 4 Department of Medical Genetics, Faculty of Sciences of Rabat, University Mohamed V Agdal, Morocco, Africa,
Correspondence Address:
Abdelhafid Natiq Département de Génétique Médicale, Institut National d'Hygiène, 27 Avenue, Ibn Batouta, B. P. 769, 11400, Rabat, Morocco
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DOI: 10.4103/0971-6866.132767
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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. |