MYBPC3 encodes the cardiac isoform of myosin-binding protein C. Myosin-binding protein C is a myosin-associated protein found in the cross-bridge-bearing zone (C region) of A bands in striated muscle. MYBPC3, the cardiac isoform, is expressed exclussively in heart muscle.

MYBPC gene is linked to CMH4 and demonstrated a splice donor mutationin 1 family with familial hypertrophic cardiomyopathy and a duplication mutation in a second. Both mutations were predicted to disrupt the high-affinity, C-terminal myosin-binding domain of cardiac MyBP-C. Again, findings demonstrated that as in the case of the 3 forms that had been defined in molecular terms previously, familial hypertrophic cardiomyopathy is a disease of the sarcomere.