Molecular Analysis of Acquired Myoadenylate Deaminase Deficiency in Polymyositis (Idiopathic Inflammatory Myopathy)

Myoadenylate deaminase (mAMPD) deficiency occurs in primary (inherited) and secondary (acquired) forms (1). Clinically, inherited mAMPD deficiency is accompanied by exercise intolerance, muscle cramping, and myalgia. At the molecular level inherited mAMPD deficiency is characterized by normal transcript abundance without any immunoreactive mAMPD peptide (2). Recently, inherited mAMPD deficiency has been defined as a single point mutation in the human gene for myoadenylate deaminase (Ampdl) and is estimated to occur in 2% of the normal population (3).