Human myoadenylate deaminase deficiency.

Abstract

This entity was first described, in 5 patients, in 1978, as the consequence of the introduction of an effective histoenzymatic stain1 for adenylate deaminase in frozen muscle biopsies. That report2 established the following: (1) The deficiency state was quite common, occurring in 1–2% of muscle biopsies, and accompanied by relatively mild, though persistent, symptoms of exertional myalgia. (2) Application of a sensitive solution assay3 verified that all 5 cases had less than 5% of the specific activity of adenylate deaminase in normal muscle biopsies, thus validating the histoenzymatic stain as a diagnostic tool. (3) There was no evidence of an enzyme inhibitor, by crossmixing studies of normal and deficient homogenates. (4) Affected patients had normal levels of adenylate deaminase in their red cells, indicating separate genetic control of the two isozymes. (5) Affected patients had normal skeletal muscle architecture and normal levels of other enzymes, indicating that the enzyme deficiency was specific, and was clearly not the cause of muscular dystrophy, as had often been suggested. (6) A simple provocative procedure, the lactateammonia-exercise-ratio (LAER test) demonstrated the physiological deficit in affected patients, and could be used for clinical diagnosis. (7) Skeletal muscle adenylate deaminase could be separated and identified, in its native state, by proper application of PAGE and the catalytic stain.KeywordsMuscular DystrophyMuscle BiopsyDeficiency StateMalignant HyperthermiaPurine Nucleotide CycleThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.