title: Array comparative genomic hybridization identifies a heterozygous deletion of the entire KCNJ2 gene as a cause of sudden cardiac death.
abstract: BACKGROUND
  Large gene rearrangements, not detectable by standard molecular genetic sequencing techniques, are present in a minority of patients with long QT syndrome. We aimed to screen for large rearrangements in genes responsible for long QT syndrome as part of the molecular autopsy of a 36-year-old woman who died suddenly and had a negative autopsy. A retrospective analysis of an ECG identified a long QT interval, but sequencing of known LQT genes was uninformative.
  
  
  RESULTS
  Array comparative genomic hybridization was used to screen for deletions and duplications in 101 genes implicated in cardiac disorders and sudden death using a postmortem blood sample. A 542 kb deletion encompassing the entire KCNJ2 gene was identified in the decedent. The mother had electrocardiographic U-wave changes consistent with Andersen-Tawil syndrome and exaggerated by exercise but none of the characteristic noncardiac features. Fluorescence in situ hybridization confirmed the deletion in the decedent and established its presence in the mother.
  
  
  CONCLUSIONS
  A novel application of array comparative genomic hybridization and fluorescence in situ hybridization has identified that long QT syndrome and sudden cardiac death may occur as a result of a deletion of an entire gene. The case also supports recent research suggesting that noncardiac features of Andersen-Tawil syndrome occur only with missense or minor gene rearrangements in the KCNJ2 gene, resulting in a dominant negative effect on Kir2.x channels.
authors.affiliation: Diagnostic Genetics, LabPlus, Auckland, New Zealand.
authors.forename: Renate
authors.initials: R
authors.lastname: Marquis-Nicholson
authors.forename: Debra O
authors.initials: DO
authors.lastname: Prosser
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Love
authors.forename: Liangtao
authors.initials: L
authors.lastname: Zhang
authors.forename: Ian
authors.initials: I
authors.lastname: Hayes
authors.forename: Alice M
authors.initials: AM
authors.lastname: George
authors.forename: Jackie R
authors.initials: JR
authors.lastname: Crawford
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Skinner
authors.forename: Donald R
authors.initials: DR
authors.lastname: Love
mesh_terms: D000328:Adult; D002886:Chromosomes, Human, Pair 17; D055028:Comparative Genomic Hybridization; D016757:Death, Sudden, Cardiac / Q000209:etiology*; D004562:Electrocardiography; D005260:Female; D017353:Gene Deletion; D006579:Heterozygote; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008133:Long QT Syndrome / Q000235:genetics* / Q000473:pathology; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics* / Q000378:metabolism; D012189:Retrospective Studies
chemical_list: C489457:KCNJ2 protein, human; D024661:Potassium Channels, Inwardly Rectifying
keywords: Andersen syndrome; arrhythmias, cardiac; comparative genomic hybridization; death, sudden, cardiac; long QT syndrome; molecular diagnostic techniques