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Biochemical and molecular basis for mitochondrial cardiomyopathy in neonates and children
Author(s) -
MarinGarcia J.,
Ananthakrishnan R.,
Goldenthal M. J.,
Pierpont M. E.
Publication year - 2000
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1023/a:1005638231195
Subject(s) - heteroplasmy , mitochondrial dna , cardiomyopathy , genetics , biology , mitochondrial disease , mutation , pathophysiology , mitochondrion , bioenergetics , medicine , gene , endocrinology , heart failure
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.