title: Characterization of a novel transcript of the EHMT1 gene reveals important diagnostic implications for Kleefstra syndrome.
abstract: The core phenotype of Kleefstra syndrome (KS) is characterized by intellectual disability, childhood hypotonia, and a characteristic facial appearance. This can be caused by either submicroscopic 9q34 deletions or loss of function mutations of the EHMT1 gene. Remarkably, in three patients with a clinical suspicion of KS, molecular cytogenetic analysis revealed an interstitial 9q34 microdeletion proximal to the coding region of the EHMT1 gene based on the NM_ 024757.3 transcript. Because we found a mono-allelic EHMT1 transcript suggestive for haploinsufficiency of EHMT1 in two of these patients tested, we hypothesized that a deletion of regulatory elements or so far unknown coding sequences in the 5' region of the EHMT1 gene, might result in a phenotype compatible with KS. We further characterized the molecular content of deletions proximal to the transcript NM_ 024757.3 and confirmed presence of a novel predicted open reading frame comprising 27 coding exons (NM_ 024757.4). Further analysis showed that all three deletions included the presumed novel first exon of the EHMT1 gene. Subsequent testing of 75 individuals without previously detectable EHMT1 aberrations showed one additional case with a deletion comprising only this 5' part of the gene. These results have important implications for the genetic screening of KS and for studies of the functional significance of EHMT1.
authors.affiliation: Department of Human Genetics, RUNMC, Nijmegen, The Netherlands.
authors.forename: Willy M
authors.initials: WM
authors.lastname: Nillesen
authors.forename: Helger G
authors.initials: HG
authors.lastname: Yntema
authors.forename: Marco
authors.initials: M
authors.lastname: Moscarda
authors.forename: Nienke E
authors.initials: NE
authors.lastname: Verbeek
authors.forename: Louise C
authors.initials: LC
authors.lastname: Wilson
authors.forename: Frances
authors.initials: F
authors.lastname: Cowan
authors.forename: Marga
authors.initials: M
authors.lastname: Schepens
authors.forename: Annick
authors.initials: A
authors.lastname: Raas-Rothschild
authors.forename: Orly
authors.initials: O
authors.lastname: Gafni-Weinstein
authors.forename: Marcella
authors.initials: M
authors.lastname: Zollino
authors.forename: Raymon
authors.initials: R
authors.lastname: Vijzelaar
authors.forename: Giovanni
authors.initials: G
authors.lastname: Neri
authors.forename: Marcel
authors.initials: M
authors.lastname: Nelen
authors.forename: Hans van
authors.initials: Hv
authors.lastname: Bokhoven
authors.forename: Jacques
authors.initials: J
authors.lastname: Giltay
authors.forename: Tjitske
authors.initials: T
authors.lastname: Kleefstra
mesh_terms: D020121:5' Untranslated Regions; D000328:Adult; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics*; D055028:Comparative Genomic Hybridization; D005091:Exons / Q000235:genetics; D019066:Facies; D005260:Female; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics*; D006801:Humans; D008607:Intellectual Disability / Q000175:diagnosis* / Q000235:genetics; D009123:Muscle Hypotonia / Q000175:diagnosis* / Q000235:genetics; D009154:Mutation / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D017384:Sequence Deletion / Q000235:genetics; D013577:Syndrome
chemical_list: D020121:5' Untranslated Regions; C455847:EHMT1 protein, human; D011495:Histone-Lysine N-Methyltransferase