Gene expression signatures in polyarticular juvenile idiopathic arthritis demonstrate disease heterogeneity and offer a molecular classification of disease subsets. - Griffin TA; Barnes MG; Ilowite NT; Olson JC; Sherry DD; Gottlieb BS; Aronow BJ; Pavlidis P; Hinze CH; Thornton S; Thompson SD; Grom AA; et al. (Arthritis & Rheumatism, 2009)