Newborn screening for primary immunodeficiencies: Focus on Severe Combined Immunodeficiency (SCID) and other severe T-cell lymphopenias

Abstract

Primary immunodeficiencies (PID) are congenital disorders of immune competence, which are mainly characterized by a pathological susceptibility to infection. More than 240 PID disease entities have been defined so far, accounting for a broad spectrum of clinical symptoms and severity. Severe PID are increasingly becoming appreciated as a relevant health problem, and diagnostic procedures and screening profiles to allow earliest possible diagnosis on a population scale have already been developed in the USA and few European countries. The most severe PID are characterized by significant mortality in the first years of life, as well as serious morbidity with irreversible organ damage. This applies in particular to PID that are defined by the absence or functional anergy of T-lymphocytes (severe combined immunodeficiency; SCID) or B-lymphocytes (e.g., X-linked agammaglobulinemia; XLA). A strategy to improve the outcome of severe PID by prompt diagnosis and immediate adequate treatment is screening newborns for the presence of T and B cells.