Discovery of new genetic cause severe combined immunodeficiency (SCID)

Severe combined immunodeficiency (SCID) is an inherited disease sometimes known as 'Boy in the bubble syndrome', because the patient lacks one or more type of immune cell, making them very susceptible to infections.

Dik van Gent and colleagues, at Erasmus Medical Center, The Netherlands, have now identified a new genetic cause of SCID characterized by a lack of T cells and B cells (T–B– SCID). Specifically, they identified a patient with T-B- SCID who has a mutation in the gene DNA-PKcs.

Further analysis revealed the reason that the mutant DNA-PKcs protein generated as a result of the DNA-PKcs genetic mutation caused SCID: it was unable to activate another protein (known as Artemis) that is essential for the development of T cells and B cells. Importantly, the mutant DNA-PKcs protein retained the ability to perform one of the main functions of normal DNA-PKcs protein (a process known as kinase activity). The authors therefore conclude that clinicians with patients who have T–B– SCID should consider the possibility that mutations in the gene DNA-PKcs might be the cause of disease, even in those individuals who have normal DNA-PKcs kinase activity.