Turul, TubaTezcan, İlhanArtaç, Hasibede Bruin-Versteeg, SandraBarendregt, Barbara H.Reisli, İsmailSanal, Özden2020-03-262020-03-2620090340-6199https://dx.doi.org/10.1007/s00431-008-0718-xhttps://hdl.handle.net/20.500.12395/23356One of the severe combined immunodeficiencies (SCIDs), which is caused by a genetic defect in the signal transduction pathways involved in T-cell activation, is the ZAP70 deficiency. Mutations in ZAP70 lead to both abnormal thymic development and defective T-cell receptor (TCR) signaling of peripheral T-cells. In contrast to the lymphopenia in most SCID patients, ZAP70-deficient patients have lymphocytosis, despite the selective absence of CD8(+)T-cells. The clinical presentation is usually before 2 years of age with typical findings of SCID. Here, we present three new ZAP70-deficient patients who vary in their clinical presentation. One of the ZAP70- deficient patients presented as a classical SCID, the second patient presented as a healthy looking wheezy infant, whereas the third patient came to clinical attention for the eczematous skin lesions simulating atopic dermatitis with eosinophilia and elevated immunoglobulin E (IgE), similar to the Omenn syndrome. This study illustrates that awareness of the clinical heterogeneity of ZAP70 deficiency is of utmost importance for making a fast and accurate diagnosis, which will contribute to the improvement of the adequate treatment of this severe immunodeficiency.en10.1007/s00431-008-0718-xinfo:eu-repo/semantics/openAccessSevere combined immunodeficiencyZAP70T-cell receptor signalingT-cellsArticle1681879318509675Q1WOS:000261178200014Q2