Metabolism of adenine and adenosine in erythrocytes of patients with myotonic muscular dystrophy (MMD).

Abstract

Myotonic muscular dystrophy (MMD) is an inherited disease with an autosomal dominant trait with high penetrance and a variable clinical presentation. The symptoms may include myotonia, weakness and dystrophy of skeletal muscles, cardiac arrhythmias, dysphagia and abdominal pain, testicular atrophy, hyperinsulinemia in response to a glucose load, cataract and mental retardation. Although the inborn error of metabolism is unknown, it is assumed that the cellular plasma membranes in many organs are impaired. The basis of the altered membrane properties might be a decreased phosphorylation of membrane proteins by the enzyme protein kinase which was demonstrated in muscle biopsies (1) and erythrocytes of patients with MMD (2). Previous studies showed abnormal adenine metabolism of erythrocytes in MMD with a reduced adenine incorporation into ATP and ADP and an increased formation of AMP (3). The authors discussed an impaired adenine uptake responsible for the reduced formation of ATP.