title: Low-level mosaicism of a de novo derivative chromosome 9 from a t(5;9)(q35.1;q34.3) has a major phenotypic impact.
abstract: Microdeletion and microduplication syndromes are well-known causes of developmental delay and/or malformations of differing severity. Although homogeneous abnormalities can now be detected relatively easily using microarray technologies, they are more difficult to detect and interpret in cases of mosaicism. Here, we report on a male infant with a mosaic de novo derivative chromosome 9, featuring a 10.2 Mb 5q35 duplication (including the NSD1 gene) and a 687 kb 9q34 deletion (including EHMT1). The infant presented developmental delay, short stature, brachy/plagiocephaly and hyperactivity. The proportion of abnormal cells was 50% in saliva (in a microarray analysis) and 25% in lymphocytes (in a FISH analysis). Despite the low-level mosaicism in lymphocytes, this imbalance appears to be responsible for a distinctive phenotype (suggesting the presence of variable clinical expression and/or major somatic mosaicism).
authors.affiliation: Service de Cytogénétique, Centre Hospitalier Intercommunal de Poissy Saint-Germain-en-Laye, 10 rue du Champ Gaillard, F-78303 Poissy, France; UPCG, UFR des Sciences de la Santé Simone Veil, 2 avenue de la source de la Bièvre, F-78180 Montigny le Bretonneux, France. Electronic address: herve.berenice@gmail.com.
authors.forename: B
authors.initials: B
authors.lastname: Hervé
authors.affiliation: Service de Cytogénétique, Centre Hospitalier Intercommunal de Poissy Saint-Germain-en-Laye, 10 rue du Champ Gaillard, F-78303 Poissy, France.
authors.forename: J
authors.initials: J
authors.lastname: Roume
authors.affiliation: Service de Cytogénétique, Centre Hospitalier Intercommunal de Poissy Saint-Germain-en-Laye, 10 rue du Champ Gaillard, F-78303 Poissy, France.
authors.forename: S
authors.initials: S
authors.lastname: Cognard
authors.affiliation: Service de Cytogénétique, Centre Hospitalier Intercommunal de Poissy Saint-Germain-en-Laye, 10 rue du Champ Gaillard, F-78303 Poissy, France.
authors.forename: D
authors.initials: D
authors.lastname: Fauvert
authors.affiliation: Service de Cytogénétique, Centre Hospitalier Intercommunal de Poissy Saint-Germain-en-Laye, 10 rue du Champ Gaillard, F-78303 Poissy, France.
authors.forename: D
authors.initials: D
authors.lastname: Molina-Gomes
authors.affiliation: Service de Cytogénétique, Centre Hospitalier Intercommunal de Poissy Saint-Germain-en-Laye, 10 rue du Champ Gaillard, F-78303 Poissy, France; UPCG, UFR des Sciences de la Santé Simone Veil, 2 avenue de la source de la Bièvre, F-78180 Montigny le Bretonneux, France.
authors.forename: F
authors.initials: F
authors.lastname: Vialard
mesh_terms: D002675:Child, Preschool; D002872:Chromosome Deletion; D002895:Chromosomes, Human, Pair 5 / Q000235:genetics*; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics*; D019465:Craniofacial Abnormalities / Q000175:diagnosis / Q000235:genetics*; D017353:Gene Deletion; D020440:Gene Duplication; D006330:Heart Defects, Congenital / Q000175:diagnosis / Q000235:genetics*; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics; D006801:Humans; D008607:Intellectual Disability / Q000175:diagnosis / Q000235:genetics*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D008297:Male; D009030:Mosaicism; D009687:Nuclear Proteins / Q000235:genetics; D010641:Phenotype
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; C455847:EHMT1 protein, human; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; C113272:NSD1 protein, human
keywords: 5q35 duplication; 9q34 deletion; Kleefstra syndrome; Microarray; Mosaicism; Reversed Sotos syndrome; Segmental imbalances