Anti-Sp4 autoantibodies co-occur with anti-TIF1 and are associated with distinct clinical features and immunogenetic risk factors in juvenile myositis.

Anti-Sp4 autoantibodies were found in patients with juvenile-onset IIM, predominantly those with co-existing anti-TIF1 autoantibodies. Patients with anti-Sp4 autoantibodies represent a phenotypic subset of anti-TIF1 autoantibody-positive myositis characterized by frequent Raynaud's phenomenon and less pronounced muscle involvement, similar to adults with these autoantibodies. Novel immunogenetic risk factors for White patients with IIM were identified among juveniles with anti-Sp4 autoantibodies. This article is protected by copyright. All rights reserved.