A variant in the carboxyl-terminus of connexin 40 alters GAP junctions and increases risk for tetralogy of Fallot

Valentina Guida, Rosangela Ferese, Marcella Rocchetti, Monica Bonetti, Anna Sarkozy, Serena Cecchetti, Vania Gelmetti, Francesca Lepri, Massimiliano Copetti, Giuseppe Lamorte, Maria Cristina Digilio, Bruno Marino, Antonio Zaza, Jeroen Den Hertog, Bruno Dallapiccola, Alessandro De Luca

Research output: Contribution to journalArticlepeer-review

Abstract

GJA5 gene (MIM no. 121013), localized at 1q21.1, encodes for the cardiac gap junction protein connexin 40. In humans, copy number variants of chromosome 1q21.1 have been associated with variable phenotypes comprising congenital heart disease (CHD), including isolated TOF. In mice, the deletion of Gja5 can cause a variety of complex CHDs, in particular of the cardiac outflow tract, corresponding to TOF in many cases. In the present study, we screened for mutations in the GJA5 gene 178 unrelated probands with isolated TOF. A heterozygous nucleotide change (c.793C>T) in exon 2 of the gene leading to the p.Pro265Ser variant at the carboxyl-terminus of the protein was found in two unrelated sporadic patients, one with classic anatomy and one with pulmonary atresia. This GJA5 missense substitution was not observed in 1568 ethnically-matched control chromosomes. Immunofluorescent staining and confocal microscopy revealed that cells expressing the mutant protein form sparse or no visible gap-junction plaques in the region of cell-cell contact. Moreover, analysis of the transfer of the gap junction permanent tracer lucifer yellow showed that cells expressing the mutant protein have a reduced rate of dye transfer compared with wild-type cells. Finally, use of a zebrafish model revealed that microinjection of the GJA5-p.Pro265Ser mutant disrupts overall morphology of the heart tube in the 37% (22/60) of embryos, compared with the 6% (4/66) of the GJA5 wild-type-injected embryos. These findings implicate GJA5 gene as a novel susceptibility gene for TOF.

Original languageEnglish
Pages (from-to)69-75
Number of pages7
JournalEuropean Journal of Human Genetics
Volume21
Issue number1
DOIs
Publication statusPublished - Jan 2013

Keywords

  • 1q21.1
  • congenital heart disease
  • connexin 40
  • GJA5
  • tetralogy of Fallot

ASJC Scopus subject areas

  • Genetics(clinical)
  • Genetics

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