Connexins are transmembrane proteins, which oligomerize into hexameres adjusting in hemi-channels (connexons). The docking of connexons between two neighboring cells results in the formation of intercellular channels, which are permeable to ions and small molecules¹. These channels, which are also known as gap junctions, are characterized by distinct electrophysiological properties. Various physiological and pathological conditions regulate the opening and closing of the channels². Several genetic disorders have been identified in which specific connexin genes are mutated³.

Connexin 40 (Cx40) gene consists two exons, a small untranslated exon, exon 1, and an uninterrupted coding region located in an exon 2⁴. In human and mouse species, Cx40 is expressed in various tissues and cells, such as choriocarcinoma cell lines, tonsil lymphocytes and cardiomyocytes⁵. The expression of the Cx40 gene in cardiomyocytes suggested that in the adult heart, Cx40 involved in the propagation of the electrical impulses from the atria to the ventricles. It was supported by the finding that Cx40 knockout mice developed cardiac conduction defects which matched the pattern of expression of the gene⁶.