title: Connexin43 mutation causes heterogeneous gap junction loss and sudden infant death.
abstract: BACKGROUND
  An estimated 10% to 15% of sudden infant death syndrome (SIDS) cases may stem from channelopathy-mediated lethal arrhythmias. Loss of the GJA1-encoded gap junction channel protein connexin43 is known to underlie formation of lethal arrhythmias. GJA1 mutations have been associated with cardiac diseases, including atrial fibrillation. Therefore, GJA1 is a plausible candidate gene for premature sudden death.
  
  
  RESULTS
  GJA1 open reading frame mutational analysis was performed with polymerase chain reaction, denaturing high-performance liquid chromatography, and direct DNA sequencing on DNA from 292 SIDS cases. Immunofluorescence and dual whole-cell patch-clamp studies were performed to determine the functionality of mutant gap junctions. Immunostaining for gap junction proteins was performed on SIDS-associated paraffin-embedded cardiac tissue. Two rare, novel missense mutations, E42K and S272P, were detected in 2 of 292 SIDS cases, a 2-month-old white boy and a 3-month-old white girl, respectively. Analysis of the E42K victim's parental DNA demonstrated a de novo mutation. Both mutations involved highly conserved residues and were absent in >1000 ethnically matched reference alleles. Immunofluorescence demonstrated no trafficking abnormalities for either mutation, and S272P demonstrated wild-type junctional conductance. However, junctional conductance measurements for the E42K mutation demonstrated a loss of function not rescued by wild type. Moreover, the E42K victim's cardiac tissue demonstrated a mosaic immunostaining pattern for connexin43 protein.
  
  
  CONCLUSIONS
  This study provides the first molecular and functional evidence implicating a GJA1 mutation as a novel pathogenic substrate for SIDS. E42K-connexin43 demonstrated a trafficking-independent reduction in junctional coupling in vitro and a mosaic pattern of mutational DNA distribution in deceased cardiac tissue, suggesting a novel mechanism of connexin43-associated sudden death.
authors.affiliation: Mayo Clinic, MN 55905, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Van Norstrand
authors.forename: Angeliki
authors.initials: A
authors.lastname: Asimaki
authors.forename: Clio
authors.initials: C
authors.lastname: Rubinos
authors.forename: Elena
authors.initials: E
authors.lastname: Dolmatova
authors.forename: Miduturu
authors.initials: M
authors.lastname: Srinivas
authors.forename: David J
authors.initials: DJ
authors.lastname: Tester
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Saffitz
authors.forename: Heather S
authors.initials: HS
authors.lastname: Duffy
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ackerman
mesh_terms: D000328:Adult; D000818:Animals; D015820:Cadherins / Q000378:metabolism; D015331:Cohort Studies; D018031:Connexin 43 / Q000235:genetics* / Q000378:metabolism; D051180:Desmoplakins / Q000378:metabolism; D005260:Female; D017629:Gap Junctions / Q000473:pathology* / Q000502:physiology*; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D007223:Infant; D008297:Male; D020125:Mutation, Missense; D032383:Myocytes, Cardiac / Q000473:pathology / Q000502:physiology; D018408:Patch-Clamp Techniques; D021381:Protein Transport / Q000235:genetics; D051381:Rats; D013398:Sudden Infant Death / Q000235:genetics* / Q000473:pathology*
chemical_list: D015820:Cadherins; D018031:Connexin 43; C495294:DSP protein, human; D051180:Desmoplakins; C500216:GJA1 protein, human