title: Mosaic microdeletion 18q21 as a cause of mental retardation.
abstract: We present the clinical and cytogenetic findings in an 8 year old girl with mental retardation, acquired microcephaly, delayed motor skills and stereotypical hand movements. Array comparative genomic hybridization identified a mosaic de novo deletion of approximately 7.505 Mb in chromosome region 18q21.1q21.31, resulting in the loss of one copy of the TCF4 gene as well as 29 other RefSeq genes. The deletion likely occurred early in development as this child has clinical symptoms affecting multiple organ systems, reminiscent of those observed in Pitt-Hopkins syndrome (PHS; OMIM 610954). This case represents the second known example of a mosaic deletion resulting in clinical symptoms consistent with Pitt-Hopkins syndrome, and illustrates the utility of genomic microarray analysis in detecting large mosaic imbalances that may otherwise be missed by G-band analysis.
authors.affiliation: Department of Pediatric Laboratory Medicine, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Dimitri J
authors.initials: DJ
authors.lastname: Stavropoulos
authors.forename: Daune L
authors.initials: DL
authors.lastname: MacGregor
authors.forename: Grace
authors.initials: G
authors.lastname: Yoon
mesh_terms: D000015:Abnormalities, Multiple / Q000235:genetics; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics; D002648:Child; D002887:Chromosomes, Human, Pair 18; D055028:Comparative Genomic Hybridization / Q000379:methods; D020732:Cytogenetic Analysis / Q000379:methods; D019066:Facies; D005260:Female; D017353:Gene Deletion; D006801:Humans; D006985:Hyperventilation / Q000175:diagnosis / Q000235:genetics; D008607:Intellectual Disability / Q000175:diagnosis / Q000235:genetics; D008831:Microcephaly / Q000235:genetics*; D000073940:Transcription Factor 4; D014157:Transcription Factors / Q000235:genetics
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C532096:TCF4 protein, human; D000073940:Transcription Factor 4; D014157:Transcription Factors