Previous studies have demonstrated that, in 50–60% of HCM cases, the disease is caused by mutations in at least eight genes coding for cardiac sarcomere proteins, including MYH7, MYBPC3, TNNT2, TNNI3, TPM1, ACTC1, MYL2 and MYL3, of which, the most commonly affected are the sarcomere genes MYH7 and MYBPC3. Mutations in genes encoding the Z-disc or calcium-handling proteins account for less than 1% of cases, and a further 5% of patients have metabolic disorders, neuromuscular disease, chromosome abnormalities or genetic malformation syndromes7, 8, 9. Here, MYH7 is linked to neuromuscular disease.