title: A case of sporadic infantile histiocytoid cardiomyopathy caused by the A8344G (MERRF) mitochondrial DNA mutation.
abstract: The A8344G mitochondrial DNA (mtDNA) mutation is best known for the MERRF phenotype (myoclonic epilepsy, myopathy, and ragged red fibers). We describe a sporadic case of an infant with the A8344G mtDNA mutation who presented with failure to thrive and sudden unexpected death at 11 months of age. The autopsy revealed a histiocytoid cardiomyopathy, diffuse steatosis of the liver, and bilateral retinal hypoplasia. Electron micrographs of cardiac myocytes showed striking mitochondrial hyperplasia, dispersing the sarcomeres. Special stains of frozen heart muscle showed an absence of complex IV (cytochrome c oxidase) in many of the myocytes. Both complexes I and IV of the respiratory chain were reduced in cardiac muscle. The A8344G mtDNA mutation was detected in both liver and cardiac muscle tissue. To our knowledge, this is the first description of the A8344G mtDNA mutation presenting as a sporadic case of fatal infantile cardiomyopathy and the first occurrence of this mutation associated with histiocytoid cardiomyopathy.
authors.affiliation: Department of Pathology, Children's & Women's Health Centre of BC, University of British Columbia, 4500 Oak Street, Vancouver, British Columbia, V6H 3 N1, Canada.
authors.forename: H D
authors.initials: HD
authors.lastname: Vallance
authors.forename: G
authors.initials: G
authors.lastname: Jeven
authors.forename: D C
authors.initials: DC
authors.lastname: Wallace
authors.forename: M D
authors.initials: MD
authors.lastname: Brown
mesh_terms: D009202:Cardiomyopathies / Q000235:genetics*; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial / Q000235:genetics*; D017809:Fatal Outcome; D005260:Female; D006801:Humans; D007223:Infant; D008929:Mitochondria, Heart / Q000235:genetics / Q000378:metabolism; D017240:Mitochondrial Myopathies / Q000235:genetics*; D009206:Myocardium / Q000473:pathology
chemical_list: D004272:DNA, Mitochondrial