More Severe Disease Found in Juvenile Myositis With Anti-NT5C1A Autoantibodies

Autoantibodies that recognize cytosolic 5′-nucleotidase 1A (NT5C1A) were detected in approximately 25% of patients with juvenile myositis and juvenile idiopathic arthritis (JIA), according to the results of an exploratory analysis published in the Annals of the Rheumatic Diseases. Patients with juvenile myositis with anti-NT5C1A autoantibodies typically had more severe disease compared with patients without these autoantibodies.

The study was designed to define the prevalence and clinical characteristics associated with anti-NT5C1A autoantibodies in patients with juvenile myositis. The investigators screened sera from 380 children with juvenile myositis, 30 with JIA, and 92 healthy control patients for the presence of anti-NT5C1A autoantibodies. The clinical features of participants with myositis and anti-NT5C1A autoantibodies were compared with the clinical features of patients with myositis without anti-NT5C1A autoantibodies.

Overall, anti-NT5C1A autoantibodies were detected in 27% of patients with juvenile myositis, 12% of children in the health control group (P =.002), and 27% of patients with JIA (P =.05 vs control patients).

The researchers found that participants with juvenile myositis with and without anti-NT5C1A autoantibodies had similar clinical phenotypes. Those with anti-NT5C1A autoantibody-positive myositis, however, exhibited higher rates of pulmonary symptoms at diagnosis (P =.005), required a larger number of medications (P <.001), and experienced more frequent hospitalizations (P =.01).

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The investigators concluded that additional studies are warranted to confirm the association between presence of anti-NT5C1A autoantibodies and disease severity in pediatric patients with juvenile myositis. Future research may also explore whether anti-NT5C1A autoantibodies are the result or cause of the more severe clinical manifestations of disease reported among this population.

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Yeker RM, Pinal-Fernandez I, Kishi T, et al; for the Childhood Myositis Heterogeneity Collaborative Study Group. Anti-NT5C1A autoantibodies are associated with more severe disease in patients with juvenile myositis [published online January 23, 2018]. Ann Rheum Dis. doi: 10.1136/annrheumdis-2017-212436