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Researchers from Hong Kong assessed the clinical associations seen with the anti-melanoma differentiation-associated gene 5 antibody (anti-MDA5 Ab) assay in consecutive patients with dermatomyositis (DM) and polymyositis (PM).
Twenty patients with either DM or PM who were followed in the Rheumatology Clinic of Kwong Wah Hospital, Hong Kong were recruited and underwent testing for the anti-MDA-5 antibody.
Anti-MDA5 Ab was found in 30% of patients with DM but not in DM patients. All patients with the antibody had clinically manifest amyopathic DM (CADM). They were more likely to be male, younger and with shorter disease duration.
The MDA5 Ab profile identifies a subset of CADM with rapidly progressive interstitial lung disease (RP-ILD) and digital ulcers and was unaffected by treatment.
Another recent report from the American Journal of Medicine assayed 182 PM/DM patients for antiaminoacyl-tRNA synthetase (ARS) and MDA5 antibodies (Citation source https://buff.ly/2GC0EOG).
MDA-5 positive patients were more likely to have rapidly progressive ILD (RP-ILD) (55.8% vs. 25% versus 16.9%, P < 0.001) compared to those with ARS or without either antibody profile.
Whereas treatment responses and 5 year survival was poorest in the MDA5 group, the ARS patients had the best ILD improvement and survival (98% vs 50% in MDA5 group; P < 0.001).
MDA5-ILD patients are at risk for severe pulmonary manifestations, poor response to treatment and an unfavorable prognosis.