Comparing and contrasting clinical and serological features of juvenile and adult-onset myositis: Implications for pathogenesis and outcomes

Purpose of review. To explore the different characteristics of the serological phenotypes identified in juvenile and adult myositis, consider how differences between the two groups might be explained and discuss how this enhances our understanding of disease pathogenesis. Recent findings. Current research has focussed on two main areas: First, defining the autoantibody associated disease phenotype in greater detail, particularly with regard to cutaneous disease and within specified populations such as juvenile-onset disease and different ethnic groups, and second, we have gained new insights into disease pathogenesis through studies analysing genetic associations and autoantigen expression. Summary. Although there are many clinically important differences between adult and juvenile-onset myositis, recent work has highlighted many of the similarities at least within autoantibody-defined subgroups. Viewing age at disease onset as a continuum with its own influence on disease phenotype strengthens the ability of autoantibodies to define homogenous disease groups, and may be important in understanding the relationship between autoantibodies and disease pathogenesis.