Early diagnosis of severe combined immunodeficiency (SCID) is important to
enable prompt referral to a supraregional centre for bone marrow transplant
ation before the occurrence of end organ damage secondary to infective comp
lications. This review outlines clinical, microbiological, and immunopathol
ogical clues that aid the diagnosis of SCID and emphasises the multidiscipl
inary approach needed to diagnose and treat these infants.