Maternally inherited hypertrophic cardiomyopathy: A manifestation of mitochondrial DNA mutations - Clinical course in two families

In the past decade, maternally inherited disorders have been described mani festing as hypertrophic cardiomyopathy. These are primarily associated with defects in oxidative metabolism due to an alteration in mitochondrial DNA. Although the biochemistry and molecular biology is well-defined, there is little information regarding clinical presentation and course. Reported man ifestations can be broad and can include myopathy, encephalopathy, stroke-l ike episodes, hearing loss, cardiomyopathy, multiorgan dysfunction and sudd en death. Predominant or exclusive involvement of the heart is rare. We rep ort the clinical presentations, investigations, pathologic findings, and cl inical course in two families with two mitochondrial tRNA defects with excl usive cardiac involvement and demonstrable clinical heterogeneity based on the percentage of mutant tRNA.