Elsevier

Morphologie

Volume 89, Issue 285, June 2005, Pages 71-75
Morphologie

Article original
An unusual familial chromosome 9 “variant” with variable phenotype: characterization by CGH analysisCaractérisation par CGH d’un variant familial inhabituel du chromosome 9 avec variabilité phénotypique

https://doi.org/10.1016/S1286-0115(05)83241-2Get rights and content

Summary

Heterochromatin confined to pericentromeric and secondary constriction regions plays a major role in morphological variation of chromosome 9, because of its size and affinity for pericentric inversion. We report on a 6-year-old boy with growth and language delay, minor facial anomalies and unusual chromosome 9 variant with an extra-band in the centromeric region on the conventional karyotype. Subsequent analysis by FISH and CGH identified this variant as a dicentric chromosome 9 with a duplication of the 9p12-q21 region. An identical chromosome 9 variant was found in the mild language retarded brother and in the phenotypically normal father and grandfather. The presumed mechanism accounting for the phenotypic discordance observed in this family and the usefulness of CGH in characterization of such variants are discussed. To our knowledge, this is the first investigation of an unusual chromosome 9 variant by CGH.

Résumé

Les variations de taille de la constriction secondaire et les inversions péricentriques du chromosome 9 limitées à l’hétérochromatine sont fréquentes. Nous rapportons le cas d’un garçon âgé de 6 ans qui présentait un retard de croissance et de langage, une dysmorphie faciale mineure et un variant inhabituel du chromosome 9 avec une bande supplémentaire localisée dans la région centromérique sur le caryotype standard. Les études plus poussées par FISH et CGH ont permis d’identifier ce variant comme un chromosome 9 dicentrique avec une duplication de la région 9p12-q21. Le même variant a été retrouvé chez le frère présentant un retard de langage modéré ainsi que chez le père et le grand-père, phénotypiquement normaux. Le mécanisme probable rendant compte des discordances phénotypiques dans cette famille et l’utilité de la CGH sont discutés. À notre connaissance, il s’agit de la première analyse par CGH d’un tel variant inhabituel du chromosome 9.

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