Biochemical and molecular basis for mitochondrial cardiomyopathy in neonates and children

J. Marin-Garcia, R. Ananthakrishnan, M. J. Goldenthal, M. E. Pierpont

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20 Scopus citations

Abstract

Defects in myocardial bioenergetics have been reported in patients with cardiomyopathy but their molecular basis and role in pathophysiology remain unclear. We sought to establish a molecular basis for cardiac mitochondrial respiratory enzyme abnormalities frequently present (75%) in a group of 16 children (including 2 neonates) with end-stage cardiomyopathy. Decreased specific activity levels were found in complexes I, III, IV and V but not in II, the only complex that is entirely nuclear encoded. Sequence analysis of cardiac mtDNA revealed 4 patients harbouring heteroplasmic mtDNA mutations in cytb, tRNA(Arg), and ND5 at highly conserved positions. These mutations were present neither in controls nor in patients without enzymatic defect. In addition, 4 patients exhibited marked reduction in cardiac mtDNA levels. The basis for respiratory enzyme abnormalities can be explained in a subset of our patients as a result of either pathogenic mtDNA mutation or depletion. Patients harbouring both DNA and enzymatic defects fulfil rigorous criteria defining mitochondrial cardiomyopathy.

Original languageEnglish (US)
Pages (from-to)625-633
Number of pages9
JournalJournal of Inherited Metabolic Disease
Volume23
Issue number6
DOIs
StatePublished - 2000

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