• Dilated cardiomyopathy
• echocardiography
• genetic counselling
• genetics
• hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is defined by the presence of increased ventricular wall thickness or mass in the absence of loading conditions (hypertension, valve disease) sufficient to cause the observed abnormality.1 This is the most common monogenic cardiac disorder and the most frequent cause of sudden cardiac death (SCD) in young people and trained competitive athletes. Disease prevalence among adults is approximately 0.2% (1:500) and in recent studies the annual SCD rate from HCM is approximately 1% on average, but between 4% and 5% in a subset of patients who benefit from prophylactic implantable cardioverter defibrillators (ICD). HCM is caused by mutations in at least 10 sarcomeric protein encoding genes and the inheritance is autosomal dominant, with the child of an affected parent having a 50% chance of inheriting the disease-causing allele. The HCM phenotype is dynamic and the onset of cardiac expression (left ventricular hypertrophy diagnosed by echocardiography or ECG) may be delayed until adulthood, and sometimes until 40–60 years of age, a phenomenon known as age-related penetrance. Clinically, this presents a problem when assessing families with HCM, and the currently recommended follow-up strategy involves periodic evaluation of first-degree relatives every 1–5 years (according to age and guidelines) with echocardiography and ECG.2 3 When a family member has abnormal cardiac screening, evaluation is then recommended in all first-degree relatives of this newly diagnosed patient, according to a stepwise or ‘cascade’ screening in the family.

Genetic testing may improve the management of families with HCM through various applications including the …