title: Evaluating the role of connexin43 in congenital heart disease: Screening for mutations in patients with outflow tract anomalies and the analysis of knock-in mouse models.
abstract: BACKGROUND
  GJA1 gene encodes a gap junction protein known as connexin 43 (Cx43). Cx43 is abundantly expressed in the ventricular myocardium and in cardiac neural crest cells. Cx43 is proposed to play an important role in human congenital heart disease, as GJA1 knock-out mice die neonatally from outflow tract obstruction. In addition, patients with visceroatrial heterotaxia or hypoplastic left heart syndrome were reported to have point mutations in GJA1 at residues that affect protein kinase phosphorylation and gating of the gap junction channel. However, as these clinical findings were not replicated in subsequent studies, the question remains about the contribution of GJA1 mutations in human congenital heart disease (CHD).
  
  
  METHODS
  We analyzed the GJA1 coding sequence in 300 patients with CHD from two clinical centers, focusing on outflow tract anomalies. This included 152 with Tetralogy of Fallot from over 200 patients exhibiting outflow tract anomalies, as well as other structural heart defects including atrioventricular septal defects and other valvar anomalies. Our sequencing analysis revealed only two silent nucleotide substitutions in 8 patients. To further assess the possible role of Cx43 in CHD, we also generated two knock-in mouse models with point mutations at serine residues subject to protein kinase C or casein kinase phosphorylation, sites that are known to regulate gating and trafficking of Cx43, respectively.
  
  
  RESULTS
  Both heterozygous and homozygous knock-in mice were long term viable and did not exhibit overt CHD.
  
  
  CONCLUSIONS
  The combined clinical and knock-in mouse mutant studies indicate GJA1 mutation is not likely a major contributor to CHD, especially those involving outflow tract anomalies.
authors.affiliation: Children's Hospital of Fudan University, Shanghai, China.
authors.forename: Guo-Ying
authors.initials: GY
authors.lastname: Huang
authors.forename: Li-Jian
authors.initials: LJ
authors.lastname: Xie
authors.forename: Kaari L
authors.initials: KL
authors.lastname: Linask
authors.forename: Chen
authors.initials: C
authors.lastname: Zhang
authors.forename: Xiao-Qing
authors.initials: XQ
authors.lastname: Zhao
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.forename: Guo-Min
authors.initials: GM
authors.lastname: Zhou
authors.forename: Ying-Jie
authors.initials: YJ
authors.lastname: Wu
authors.forename: Lucrecia
authors.initials: L
authors.lastname: Marquez-Rosado
authors.forename: Doff B
authors.initials: DB
authors.lastname: McElhinney
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Goldmuntz
authors.forename: Chengyu
authors.initials: C
authors.lastname: Liu
authors.forename: Paul D
authors.initials: PD
authors.lastname: Lampe
authors.forename: Bishwanath
authors.initials: B
authors.lastname: Chatterjee
authors.forename: Cecilia W
authors.initials: CW
authors.lastname: Lo