Yeker RM, et al. - Experts defined the prevalence and clinical features related to anti-NT5C1A autoantibodies in juvenile myositis. Compared with only 12% of healthy children, anti-NT5C1A autoantibodies were present in more than 1-quarter of children with juvenile myositis and JIA, suggesting that they were myositis-associated in children. More severe disease was seen in patients with juvenile myositis with anti-NT5C1A autoantibodies like adults with inclusion body myositis (IBM). Similar clinical phenotypes were noted in the patients with juvenile myositis with and without anti-NT5C1A autoantibodies. Nonetheless, greater pulmonary symptoms at diagnosis, more frequent hospitalisations and requirement of a larger number of medications was seen in the patients with anti-NT5C1A autoantibody-positive myositis.