CHD4 is a member of a family of alleged chromodomain helicase-DNA-binding proteins. Biochemically, CHD4 is a component of the nucleosome transformation and deacetylase (NuRD) complex that takes part in transcription regulation. Autoantibodies targeting the CHD4 are a serologic feature of idiopathic inflammatory myopathies (IIM). In IIM Mi-2 antibodies are characterized by diagnostic sensitivity and specificity of approximately 4-18% and 98-100%, respectively. Moreover, anti-CHD4 antibodies are related to dermatomyositis (frequency up to 31%) and have a great positive predictive value for this type of disease subset. Anti-CHD4 are the only defined myositis-specific autoantibodies clearly focused to a nuclear target. An additional slightly outstanding feature of Mi-2 antibodies relates to their frequency in children, which is similar to that in adults.