Clinical and laboratory features of children with ES. Forty-five patients with ES were evaluated for ALPS by in vitro Fas-mediated apoptosis assay and DNTs. Black columns represent patients with defective Fas-mediated apoptosis (consistent with ALPS); gray columns, patients with normal apoptosis assays (not consistent with ALPS; A). The ordinate depicts DNTs (%), and the gray shaded bar delineates DNTs between 2.5% (upper limit of normal) and 5% (marked elevation). All patients with DNTs below 2.5% had normal apoptosis testing. All patients with DNTs more than or equal to 5%, except for patient 69, had defective Fas-mediated apoptosis. Of note, this child was found to have an identifiable genetic mutation in FAS and may represent a false negative on apoptosis testing. Severe autoimmune cytopenias (requiring immunosuppressive treatment at least twice a year), lymphadenopathy, and IgG level were predictive of ALPS (B), whereas pancytopenia trended toward predicting ALPS in ES. Of note, 4 of 21 patients ultimately found to have ALPS had no clinical evidence of lymphoproliferation. †Limited clinical data were available for ANA (performed in 20 of 21 children with ALPS and 24 of 24 without ALPS), APLA (15 of 21 with ALPS and 14 of 24 without ALPS), and IgG (15 of 21 with ALPS and 13 of 24 without ALPS). §Trend toward statistical significance. *P value reaches significance. ALPS⁺ indicates patients with defective in vitro apoptosis; ALPS⁻, patients with normal in vitro apoptosis; and PPV, positive predictive value. P values were calculated using Fisher exact test.