Brief CommunicationNewborn screening for severe T and B cell lymphopenia identifies a fraction of patients with Wiskott-Aldrich syndrome

•A fraction of WAS patients is identified by newborn screening assays for SCID.•The rate of positive screens depends on the local cutoff values and the assay method.•Awareness for WAS should be raised in newborn screening programs for severe PID.

The lack or marked reduction of recently formed T and B cells provides a basis for neonatal screening for severe combined immunodeficiencies (SCID) and X-linked agammaglobulinemia (XLA). Newborns with other conditions are also identified if a severe T or B cell lymphopenia is present at birth. We retrospectively analyzed Guthrie card samples from 11 children with Wiskott-Aldrich syndrome (WAS), a rare disease that requires early diagnosis and treatment, to determine whether combined T-cell receptor excision circle (TREC) and kappa-deleting recombination excision circle (KREC) screening could identify these patients. 4 of 11 patients showed markedly reduced TREC or KREC copy numbers in their DBS as compared to storage-time matched controls and prospectively screened Swedish and German newborns. No correlation was observed between the WAS gene mutations, the clinical severity/course and the result of the screening assay. A diagnosis of WAS should thus be considered in newborns with positive TREC or KREC screening results.