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BackgroundPrimary immunodeficiency is common among patients with autoimmune cytopenia.ObjectiveThe purpose of this study is to retrospectively identify key clinical features and biomarkers of primary immunodeficiency (PID) in pediatric patients with autoimmune cytopenias (AIC) so as to facilitate early diagnosis and targeted therapy.MethodsElectronic medical records at a pediatric tertiary care center were reviewed. We selected 154 patients with both AIC and PID (n=17), or AIC alone (n=137) for inclusion in two cohorts. Immunoglobulin levels, vaccine titers, lymphocyte subsets (T, B and NK cells), autoantibodies, clinical characteristics, and response to treatment were recorded.ResultsClinical features associated with AIC-PID included splenomegaly, short stature, and recurrent or chronic infections. PID patients were more likely to have autoimmune hemolytic anemia (AIHA) or Evans syndrome than AIC-only patients. The AIC-PID group was also distinguished by low T cells (CD3 and CD8), low immunoglobulins (IgG and IgA), and higher prevalence of autoantibodies to red blood cells, platelets or neutrophils. AIC diagnosis preceded PID diagnosis by 3 years on average, except among those with partial DiGeorge syndrome. AIC-PID patients were more likely to fail first-line treatment.ConclusionsAIC patients, especially those with Evans syndrome or AIHA, should be evaluated for PID. Lymphocyte subsets and immune globulins serve as a rapid screen for underlying PID. Early detection of patients with comorbid PID and AIC may improve treatment outcomes. Prospective studies are needed to confirm the diagnostic clues identified and to guide targeted therapy.

Autoimmune Lymphoproliferative Syndrome (ALPS), commonly caused by mutations in the FAS gene, is a disease with variable penetrance. Subjects may be asymptomatic, or they may present with lymphadenopathy, splenomegaly, cytopenias, or malignancy. Prompt recognition of ALPS is needed for optimal management. We describe a multi-generational cohort presenting with clinical manifestations of ALPS, and a previously unreported heterozygous missense variant of uncertain significance in FAS (c.758G >T, p.G253V), located in exon 9. Knowledge of the underlying genetic defect permitted prompt targeted therapy to treat acute episodes of cytopenia. This cohort underscores the importance of genetic testing in subjects with clinical features of ALPS and should facilitate the reclassification of this variant as pathogenic.