Myoadenylate deaminase (MADA) deficiency has been associated with symptoms of postexertional aches, cramps, weakness, and skeletal muscle dysfunction. Measurement of plasma lactate and ammonia concentrations after forearm ischemic exercise has been suggested as a screening test for this disorder. We performed forearm ischemic tests on 3 patients with histochemically defined MADA deficiency and 13 healthy control subjects, in a standardized fashion. Our results demonstrated that subject effort and/or performance during the exercise portion of testing is a critical variable. In addition to lactate and ammonia, plasma purine compounds (adenosine, inosine, and hypoxanthine) were measured. The finding of decreased purine release after exercise in MADA-deficient patients compared with that in normal individuals increases the specificity of the test and supports the hypothesis that disordered purine metabolism occurs in MADA deficiency.Myoadenylate deaminase (MADA) (EC 3.5.4.6) catalyzes the deamination of AMP to IMP in skeletal muscle and plays an important role in the purine

Inclusion body myositis has been described as an inflammatory myopathy with distinctive clinical and pathologic features that is refractory to treatment. Ten cases of inclusion body myositis, as defined by histopathologic findings, were reviewed to determine whether the clinical characteristics are different in patients whose disease has been defined by light and electron microscopic studies compared with those whose disease has been defined by light microscopic studies alone. The clinical characteristics of both groups of patients were similar, and 2 patients have had excellent responses to treatment. Although inclusion body myositis represents a histologic subset of polymyositis, from a clinical perspective, it must be considered a nonspecific designation. Despite a generally poor prognosis, therapeutic intervention is still warranted.

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