Connexin43 Mutation Causes Heterogeneous Gap Junction Loss and Sudden Infant Death
Background—An estimated 10-15% of sudden infant death syndrome (SIDS) may stem from channelopathy-mediated lethal arrhythmias. Loss of the GJA1-encoded gap junction channel protein connexin43 (Cx43) 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.
Methods and Results—GJA1 open reading frame mutational analysis was performed using PCR, DHPLC, and direct DNA sequencing on DNA from 292 SIDS cases. Immunofluorescence and dual whole cell patch-clamp studies were performed to determine 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 male and a 3-month-old white female, respectively. Analysis of the E42K victim's parental DNA demonstrated a de novo mutation. Both mutations involved highly conserved residues and were absent in over 1000 ethnic-matched reference alleles. Immunofluorescence demonstrated no trafficking abnormalities for either mutation and S272P demonstrated wildtype junctional conductance. However, junctional conductance measurements for the E42K mutation demonstrated a loss-of-function not rescued by wildtype. Moreover, the E42K victim cardiac tissue demonstrated a mosaic immunostaining pattern for Cx43 protein.
Conclusions—This study provides the first molecular and functional evidence implicating a GJA1 mutation as a novel pathogenic substrate for SIDS. E42K-Cx43 demonstrated a trafficking-independent reduction in junctional coupling in vitro as well as demonstrating a mosaic pattern of mutational DNA distribution in deceased cardiac tissue, suggesting a novel mechanism of Cx43-associated sudden death.
- Received July 27, 2011.
- Accepted November 23, 2011.
- Copyright © 2011, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited