Screening for antibodies against the NXP2 antigen is carried out to investigate polymyositis, dermatomyositis, and overlay syndrome.
Antibodies against the NXP2 protein, also known as MJ antibodies, can be detected in approximately 20% of children and young adults with myositis, often with severe muscle pain (atrophy). It also presents with calcifications, ulcers and vasculitis. Myxitis with positive NXP2 antibodies often responds well to treatment and is not associated with interstitial lung disease or malignancy.
NXP2 antigen corresponds to Nuclear Matrix Protein 2 (Nuclear Matrix Protein 2).