Mitochondrial DNA-related cardiomyopathy and hearing loss

Mitochondrial DNA-related cardiomyopathy and hearing loss (also known as maternally inherited cardiomyopathy and hearing loss, or mitochondrial cardiomyopathy with sensorineural deafness) is a rare genetic condition caused by pathogenic variants in mitochondrial DNA (mtDNA). Because mitochondria are the energy-producing structures within cells, organs with high energy demands — particularly the heart and the inner ear — are preferentially affected. The condition is characterized by hypertrophic or dilated cardiomyopathy (thickening or weakening of the heart muscle) combined with sensorineural hearing loss, which may range from mild to profound. The cardiac manifestations can include progressive heart failure, arrhythmias, and exercise intolerance. Hearing loss is typically bilateral and may precede, accompany, or follow the onset of cardiac symptoms. Additional features may include skeletal myopathy, lactic acidosis, and neurological involvement in some patients, reflecting the systemic nature of mitochondrial dysfunction. Age of onset is variable, ranging from childhood to adulthood, and clinical severity can differ significantly even among members of the same family due to heteroplasmy — the proportion of mutant versus normal mitochondrial DNA in different tissues. Several mtDNA point mutations have been associated with this phenotype, including variants in mitochondrial tRNA genes. There is no curative treatment currently available. Management is supportive and multidisciplinary, involving standard heart failure therapies (such as ACE inhibitors, beta-blockers, and diuretics), cardiac monitoring, hearing aids or cochlear implants for hearing loss, and avoidance of mitochondrial toxins including certain aminoglycoside antibiotics. Cardiac transplantation may be considered in severe cases. Coenzyme Q10 and other mitochondrial cofactor supplements are sometimes used, though evidence for their efficacy remains limited.

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