Connexin 40 (Cx40) gene consists two exons, a small untranslated exon, exon 1, and an uninterrupted coding region located in an exon 2. 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 gene.