MYH7 and Abnormal cardiac septum morphology: First, the PR linkage peak on chromosome 14 contains damaging variants in the alpha and beta subunits of cardiac myosin MYH6 and MYH7. Previous studies showed that genetic variants in these two genes have been found in hypertrophic cardiomyopathy (Anan et al., 1994; Lankford et al., 1995; Rayment et al., 1995; Niimura et al., 2002; Carniel et al., 2005), dilated cardiomyopathy (Kamisago et al., 2000; Carniel et al., 2005) and atrial septal defect (Ching et al., 2005).