Profile of patients with Juvenile Dermatomyositis and Anti-MDA5 autoantibodies.

Abstract

Anti-MDA5 autoantibody-positive dermatomyositis (MDA5-DM) is associated with clinically amyopathic forms and rapidly progressive interstitial lung disease (ILD); however, data in children are limited. In this study, we described our cohort of anti-MDA5-positive juvenile DM (MDA5-JDM) from a tertiary care center in North India. We performed a retrospective analysis of children with MDA5-JDM who were diagnosed and followed up at our center and compared them with our anti-MDA5-negative cohort. We also compared the published literature on MDA5-DM with the juvenile cohort. Of 66 children with JDM who underwent testing for MSA, 10(15.5%) had anti-MDA5 positivity. The mean age at onset of clinical manifestations was 8.4 years; male: female ratio was 7:3. Five of nine patients who underwent screening HRCT chest had ILD; one amongst them had a fatal rapidly progressive disease. Children with MDA5-JDM had significantly more arthralgia/arthritis (p = 0.006) and ILD (p = 0.0005) compared to anti-MDA5 negative JDM in our cohort. While MDA5-DM had high rates of Raynaud's phenomenon (p = 0.04) and pulmonary involvement (p = 0.001), juvenile patients had a higher prevalence of constitutional symptoms (p = 0.01), skin manifestations (p = 0.003), arthritis (p = 0.001), and muscle weakness (p = 0.001). Arthritis and ILD are commonly seen with MDA5-JDM; however, the frequency of ILD and clinically amyopathic forms are less common compared to adult counterparts. The frequency of anti-MDA5 antibodies in a North Indian cohort of JDM is much lower (15.5%) compared to adult studies in dermatomyositis from Southeast Asia (~25%). Incidence of interstitial lung disease (ILD) and arthritis is high in anti-MDA5 autoantibody-positive JDM. Rates of a rapidly progressive form of ILD and clinically amyopathic dermatomyositis are much lower in children compared to adults with anti-MDA5-associated dermatomyositis.