Painful myositis in the anti-synthetase syndrome with anti-PL12 antibodies

Excerpt

Sir, the idiopathic inflammatory myopathies (IIMs) are characterised by muscle weakness, electromyography (EMG), histological and biochemical features of muscle inflammation. Their classification into clinicoserological syndromes is evolving in light of the myositis-associated autoantibody panel [1]. Anti-cytoplasmic aminoacyl-tRNA synthetase (ARS) antibodies are detected in 25–30% patients with IIMs [2]. These enzymes catalyse the binding of amino acids to their cognate tRNA molecules. ARS are frequently associated with extra-muscular manifestations (anti-synthetase syndrome, ASS) that include interstitial lung disease (ILD), non-erosive arthritis, fever, Raynaud’s phenomenon and mechanic’s hands [2]. Jo–1 (histidyl-tRNA-synthetase) is the most common autoantigenic target (20% of patients with IIMs) [2], whereas anti-PL12 antibodies (alanyl-tRNA synthetase) occur in less than 3% of cases [1]. …