Another family with a euchromatic duplication variant of 9q13-q21.1 Derived from segmentally duplicated pericentromeric euchromatin

Barber, J. C. K., Rodrigues, R., Maloney, V. K., Taborda, F., Rodrigues, M. do C. and Bateman, M. S. (2013) Another family with a euchromatic duplication variant of 9q13-q21.1 Derived from segmentally duplicated pericentromeric euchromatin. Cytogenetic and Genome Research, 141 (4), 64-69. (doi:10.1159/000350870). (PMID:23651944)

Abstract

Microscopically visible copy number variations within the proximal short arm heterochromatin and proximal long arm of chromosome 9 have been described as euchromatic variants (EVs) and are derived from extensive segmental duplications (SDs) that map to both the proximal short and long arms of chromosome 9. Recently, 3-4 additional copies of an SD cassette were found in 2 families with duplication EVs of 9q13-q21. Here, we report a third family with a duplication EV of 9q13-q21.1 that was ascertained at prenatal diagnosis for advanced maternal age and found in the fetus and her phenotypically normal mother. Dual-colour fluorescence in situ hybridization with bacterial artificial chromosomes RP11-246P17 and RP11-211E19 was consistent with the EV chromosome having 1-2 additional copies of a similar SD cassette, except that the SD-boundary clone RP11-88I18 was not apparently included. It is important to distinguish the 9q13-q21.1 EVs from possible pathogenic imbalances of chromosome 9, especially at prenatal diagnosis, as these EVs have no established phenotypic or reproductive consequences. The nature of the G-dark bands in 9q13-q21 EVs is briefly discussed.

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