Diastolic dysfunction without left ventricular hypertrophy is an early finding in children with hypertrophic cardiomyopathy-causing mutations in the β-myosin heavy chain, α-tropomyosin, and myosin-binding protein C genes

In children with HCM-causing mutations, signs of diastolic dysfunction are found in about half of the cases, as LVH is present only in small percentage of these children.