MYH6 and Abnormal cardiac septum morphology: For example, dominant variants affecting myosin heavy chain 6 (MYH6) are associated with cardiomyopathy and atrial septal defects (Ching et al., 2005; Hershberger et al., 2010), whereas recessive variants in MYH6 are found in 11% of individuals with Shone syndrome, which is characterized by valve defects and multiple levels of left ventricular obstruction (Jin et al., 2017).