Cardiac amyloidosis are related to the accumulation of fibrillar proteins in the extracellular leading to disruption of the cardiac tissue architecture. Amyloidosis in transthyretin (TTR) are the most common hereditary amyloidosis but remain poorly studied at heart. This is serious and deadly. The prevalence of TTR amyloidosis is probably underestimated in hypertrophic cardiomyopathy (HCM) often of unknown etiology because of the lack of systematic implementation of myocardial biopsy because of their side effects.

A systematic screening of TTR mutations within the MHC would diagnose cardiac amyloidosis in TTR and improve the care of patients and their families.

The detection of this disease is important because this disease is fatal and a new treatment to prevent the accumulation of TTR is now available (Tafamidis). This drug has proved effective in stabilizing neurological damage.

Depending on the number of patient with cardiac amyloidosis in TTR detected, the prospect will begin a clinical trial to test the effectiveness of a new treatment to prevent the increase in mass of the left ventricle wall objectified resonance nuclear Magnetic.

Inclusion Criteria:

• Patients with cardiomyopathy defined by an ultrasound thickness of the left ventricle >= 13 mm if familial form or >= 15 mm if sporadic form.
• Patients with a signed consent authorizing the specific blood test for genetic sequencing to look for abnormal TTR gene

Exclusion Criteria:

• Patients with a diagnosis of cardiomyopathy already determined or related already diagnosed.
• Significant aortic stenosis (≤ 1 cm ²)

The study population is that of patients with hypertrophic cardiomyopathy in France whose origin has not yet been determined.