title: Another family with a euchromatic duplication variant of 9q13-q21.1 derived from segmentally duplicated pericentromeric euchromatin.
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.
authors: Department of Human Genetics and Genomic Medicine, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK. john.barber@soton.ac.uk
authors: J C K
authors: JC
authors: Barber
authors: R
authors: R
authors: Rodrigues
authors: V K
authors: VK
authors: Maloney
authors: F
authors: F
authors: Taborda
authors: M
authors: M
authors: do C Rodrigues
authors: M S
authors: MS
authors: Bateman
mesh_terms: D059786:Abnormal Karyotype; D002503:Centromere / Q000235:genetics*; D043171:Chromosomal Instability; D002871:Chromosome Banding; D058674:Chromosome Duplication; D022202:Chromosomes, Artificial, Bacterial; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics*; D022041:Euchromatin / Q000235:genetics*; D005260:Female; D006570:Heterochromatin / Q000235:genetics; D006801:Humans; D007231:Infant, Newborn; D008677:Metaphase; D010641:Phenotype; D011247:Pregnancy; D011296:Prenatal Diagnosis
chemical_list: D022041:Euchromatin; D006570:Heterochromatin