Furthermore, measurements of INa in HEK293 cells expressing DCM-associated variants R222Q and I1835T using whole-cell voltage clamp technique, have revealed that common polymorphisms H558R and Q1077del are relevant for their phenotypic expression and have a large impact on the NaV1.5 biophysical phenotypes [43]. Here, SCN5A is linked to familial dilated cardiomyopathy.