title: Partial deletion of TCF4 in three generation family with non-syndromic intellectual disability, without features of Pitt-Hopkins syndrome.
abstract: Mutations in TCF4 (basic helix-loop-helix transcription factor 4), a gene with complex organization and multiple transcription initiation sites, are usually associated with Pitt-Hopkins syndrome (PTHS). However, a translocation encompassing the 5' end of TCF4 and several point mutations have been linked to non-syndromic intellectual disability (NSID). Here we describe a family with autosomal dominantly inherited NSID in seven relatives with a partial deletion of TCF4, disrupting the 5' end of the gene, predicted to result in the reduction of the number of mRNAs that can be produced by alternative transcription initiation. Functional studies indicate that it leads to reduced levels of transcripts coding for TCF4 protein isoforms with a nuclear localization signal, which may be relevant to the phenotype. The findings in our family support the notion that the position of the mutation in TCF4 is relevant to the phenotype, with those mutations in the 5' region, cassette exons and regions not affecting the important functional domains being linked to NSID rather than PTHS. We suggest that screening for mutations in TCF4 could be considered in the investigation of NSID.
authors.affiliation: West of Scotland Clinical Genetics Service, Level 2A Laboratory Medicine Building, Queen Elizabeth University Hospital, 1345 Govan Road, Glasgow, G51 4TF, UK. Electronic address: mira.kharbanda@ggc.scot.nhs.uk.
authors.forename: Mira
authors.initials: M
authors.lastname: Kharbanda
authors.affiliation: Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, Tallinn, 12618, Estonia.
authors.forename: Kaja
authors.initials: K
authors.lastname: Kannike
authors.affiliation: South East of Scotland Department of Clinical Genetics, Molecular Medicine Centre, Western General Hospital, Edinburgh, UK.
authors.forename: Anne
authors.initials: A
authors.lastname: Lampe
authors.affiliation: Department of Clinical Genetics, University of Dundee, Ninewells Hospital and Medical School, Dundee, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Berg
authors.affiliation: Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, Tallinn, 12618, Estonia.
authors.forename: Tõnis
authors.initials: T
authors.lastname: Timmusk
authors.affiliation: Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, Tallinn, 12618, Estonia.
authors.forename: Mari
authors.initials: M
authors.lastname: Sepp
mesh_terms: D020121:5' Untranslated Regions; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics*; D005091:Exons / Q000235:genetics; D019066:Facies; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000235:genetics / Q000473:pathology; D008607:Intellectual Disability / Q000235:genetics* / Q000473:pathology; D008297:Male; D010375:Pedigree; D010641:Phenotype; D017354:Point Mutation / Q000235:genetics; D000073940:Transcription Factor 4; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D020121:5' Untranslated Regions; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C532096:TCF4 protein, human; D000073940:Transcription Factor 4; D014157:Transcription Factors
keywords: Alternative transcription; Non-syndromic intellectual disability; Pitt-Hopkins syndrome; TCF4