Familial Hypertrophic Cardiomyopathy (HCM)

It is a relatively common cardiovascular disease that affects approximately one in 500 people. It is caused by pathogenic variants in more than 11 genes that code for proteins that constitute the contractile structure or sarcomere of cardiac muscle cells.

Hypertrophic cardiomyopathy (HMC) is an autosomal dominant inherited genetic condition characterized by a thickening of the heart muscle and a myofibrillar disorganization, and consequently, causing an important risk of sudden death. It is the primary cause of sudden death in adolescence.

Despite its genetic heterogeneity, HMC has a common basic expression: that of myocardial hypertrophy and the risk of sudden death, with variable severity and largely, unforeseen. When a familial study is conducted, various degrees of expression of the illness can be found in the ecocardiographic studies of approximately 25% of the first-degree relatives.

Because it is an autosomal dominant illness, it affects men as well as women but genetic, hormonal and environmental factors cause it to be more severe in men than in women. When it appears in women, it is usually early onset and more symptomatic. It can be manifested from birth to adulthood and progresses and worsens over time.


Some patients are asymptomatic. Other malignant forms can appear early in infancy. A cardiologic study can detect pre-symptomatic family members who have positive genotypes.

Some of the symptoms associated with hypertrophic cardiomyopathy are:

  • Sudden death: usually unexpected and associated with intense exercise. It is due to a ventricular fibrillation.
  • Dyspnea (breathlessness)
  • Sincope: secondary effect to cardiac output during exercise or arrhythmia
  • Presincope: Like sincope, it is secondary effect to unsustained ventricular or atrial tachycardias and its presence an increase the risk of sudden death
  • Angina
  • Palpitations
  • Orthopnea (shortness of breath when lying down) and paroxysmal nocturnal dyspnea (waking at night short of breath)
  • Congestive heart failure
  • Dizziness


Hypertrophic cardiomyopathy affects a person´s lifestyle, especially that of young people who are in the age of carrying out sports activities. It is recommended that they limit competitive sports activities. Those who are asymptomatic, with a mild hypertrophic condition and without other sudden death risk factors should be encouraged to do other recreational sports that do not necessitate physical strength and are of low competitive nature.

Genetic studies are useful to detect those asymptomatic family members, carriers of the same mutation as in the initial case, especially in children and to be able to monitor their activities.

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