Evaluation of Suspected Immunodeficiency, Cellular

Introduction

Cellular immunodeficiency (T cell immunodeficiency) is a group of disorders caused by decreased number or function of T cells. Unusual infections or severe complications of common infections, are often seen in patients with a defect in cellular immunity. The condition can be either a primary defect of the thymus, T cell progenitors, T cell signaling, or a combined immunodeficiency with or without syndromic features (Picard et al. 2015). Severe cellular immune defects, such as severe combined immunodeficiency (SCID), complete DiGeorge syndrome (DGS), and Wiskott-Aldrich syndrome (WAS), usually manifest in infancy and can be fatal if untreated. SCID is characterized by defects in T cell number and function. Complete DGS is characterized by severe T cell lymphopenia due to thymic hypoplasia. Although presentation varies, the historic triad of DGS includes hypocalcemia, conotruncal cardiac anomaly, and hypoplastic thymus. In WAS, the classic clinical triad found in about one...