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Heart disease common in Leber’s optic neuropathy

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All patients with Leber’s hereditary optic neuropathy should be screened for cardiac abnormalities, according to a team of investigators from London who screened 24 consecutive patients and found that eight had cardiac symptoms, 14 had ECG abnormalities and five had myocardial hypertrophy. The five patients with myocardial hypertrophy, defined as a left ventricular wall thickness of 15mm or more on two dimensional echocardiography, were all from the same family, and carried the same mitochondrial DNA point mutation, known as 3460. Patients with the other two mitochondrial DNA mutations associated with Leber’s hereditary optic neuropathy (11778 and 14484) had no myocardial hypertrophy. Nor did six other members of the family carrying the 3460 mutation. Experts have long suspected that Leber’s hereditary optic neuropathy could affect the heart, and at least one previous study suggests an association with left ventricular pre excitation. This latest study is probably the first describing hypertrophic cardiomyopathy in patients with the disease.

The three mitochondrial DNA mutations 3460, 11778, and 14484 account for 90% of Leber’s hereditary optic neuropathy. All alter the encoding of complex 1, a major protein complex in the mitochondrial oxidative phosphorylation system. It’s unclear exactly why patients with the 3460 mutation seem more prone to hypertrophic cardiomyopathy than patients with the other mutations, although the three mutations affect different protein subunits in complex 1. Mutation 3460, for example, alters the ND1 subunit which causes a 30–35% decrease in ATP synthesis. Mutation 11778 alters the ND4 subunit, and mutation 14484 alters the ND6 subunit. More research is needed to investigate the impact of these different alterations on the myocardium.

Heart 2003;89:791–792.

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