Constitutively active AMP kinase mutations cause glycogen storage disease mimicking hypertrophic cardiomyopathy.

Abstract	Mutations in PRKAG2, the gene for the gamma 2 regulatory subunit of AMP-activated protein kinase, cause cardiac hypertrophy and electrophysiologic abnormalities, particularly preexcitation (Wolff-Parkinson-White syndrome) and atrioventricular conduction block. To understand the mechanisms by which PRKAG2 defects cause disease, we defined novel mutations, characterized the associated cardiac histopathology, and studied the consequences of introducing these mutations into the yeast homologue of PRKAG2, Snf4. Although the cardiac pathology caused by PRKAG2 mutations Arg302Gln, Thr400Asn, and Asn488Ile include myocyte enlargement and minimal interstitial fibrosis, these mutations were not associated with myocyte and myofibrillar disarray, the pathognomonic features of hypertrophic cardiomyopathy caused by sarcomere protein mutations. Instead PRKAG2 mutations caused pronounced vacuole formation within myocytes. Several lines of evidence indicated these vacuoles were filled with glycogen-associated granules. Analyses of the effects of human PRKAG2 mutations on Snf1/Snf4 kinase function demonstrated constitutive activity, which could foster glycogen accumulation. Taken together, our data indicate that PRKAG2 mutations do not cause hypertrophic cardiomyopathy but rather lead to a novel myocardial metabolic storage disease, in which hypertrophy, ventricular pre-excitation and conduction system defects coexist.
Authors	Michael Arad, D Woodrow Benson, Antonio R Perez-Atayde, William J McKenna, Elizabeth A Sparks, Ronald J Kanter, Kate McGarry, J G Seidman, Christine E Seidman
Journal	The Journal of clinical investigation (J Clin Invest) Vol. 109 Issue 3 Pg. 357-62 (Feb 2002) ISSN: 0021-9738 [Print] United States
PMID	11827995 (Publication Type: Comparative Study, Journal Article)
Chemical References	Carrier Proteins Multienzyme Complexes Saccharomyces cerevisiae Proteins Transcription Factors DNA Protein Kinases SNF1-related protein kinases Protein Serine-Threonine Kinases SNF4 protein, S cerevisiae AMP-Activated Protein Kinases
Topics	AMP-Activated Protein Kinases Amino Acid Sequence Base Sequence Cardiomyopathy, Hypertrophic, Familial (diagnosis, enzymology, genetics) Carrier Proteins DNA (genetics) Female Genes, Fungal Glycogen Storage Disease (diagnosis, enzymology, genetics) Humans Male Molecular Sequence Data Multienzyme Complexes (genetics) Mutation Mutation, Missense Pedigree Protein Kinases (genetics) Protein Serine-Threonine Kinases (genetics) Saccharomyces cerevisiae (enzymology, genetics, growth & development) Saccharomyces cerevisiae Proteins Sequence Homology, Amino Acid Transcription Factors (genetics) Transformation, Genetic Wolff-Parkinson-White Syndrome (diagnosis, enzymology, genetics)

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