CGH and direct diagnosis of mosaic structural chromosomal abnormalities: description of a mosaic ring chromosome 17 and review of the literature.
We report the characterisation of a de novo supernumerary chromosome marker in a mosaic state (50%) by comparative genomic hybridisation (CGH) in an 8-year-old child with hypotonia, dysmorphia and mild-to-moderate mental retardation. We describe the combined use of CGH and fluorescence in situ hybridisation (FISH) to identify the origin of the additional chromosomal material. Visual analysis of 10 CGH-metaphase spreads revealed a gain of green fluorescent signal on pericentromeric region of chromosome 17. The CGH finding was confirmed by FISH analysis using a whole chromosome 17 paint, a chromosome 17 centromeric probe and the probe coding for the Smith-Magenis locus in 17p11.2. These results show that performing both CGH and FISH in combination with classical karyotyping will certainly allow the identification of imbalanced chromosome rearrangements and, by the way, allow the identification of genes involved in mental retardation and/or malformative pathology.
Dupont
Céline
C
Service d'Histologie-Embryologie Cytogénétique Biologie de la Reproduction, Hôpital Jean Verdier (AP-HP), Avenue du 14 Juillet-93143, Bondy Cedex, France.
Pipiras
Eva
E
Chantot-Bastaraud
Sandra
S
Verloes
Alain
A
Baumann
Clarisse
C
Wolf
Jean-Philippe
JP
Benzacken
Brigitte
B
D002648:Child; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008607:Intellectual Disability / Q000235:genetics; D007621:Karyotyping; D009123:Muscle Hypotonia / Q000235:genetics; D009693:Nucleic Acid Hybridization; D012303:Ring Chromosomes; D014314:Trisomy