MYH6 encodes the alpha myosin heavy chain subunit and is predominantly expressed in the human atria.32,33 These results suggest that patients with early-onset AF associated with an MYH6 variant may have more isolated atrial involvement compared with those with an MYH7 variant and may have a genetic subtype of early-onset AF associated with lower risk of mortality. The gene discussed is MYH7; the disease is atrial fibrillation.