ABSTRACT
In Case 14 we learned about severe combined immunodeficiency (SCID) and examined the most common form-that due to an X-linked mutation in the gamma chain (gc) common to several interleukin receptors. In this type of SCID, T cells are virtually absent while B cells are present in normal numbers although they are not functional. Further examination of this phenotype also reveals an absence of natural killer (NK) cells. Thus, X-linked SCID is classified as T-B+NK-SCID.
