- severe combined immunodeficiency, severe combined immunodeficiency disease, SCID - a congenital disease affecting T cells that can result from a mutation in any one of several different genes; children with it are susceptible to infectious disease; if untreated it is lethal within the first year or two of life
--1 is a kind of immunodeficiency; monogenic disorder, monogenic disease
--1 has particulars: ADA-SCID; X-linked SCID, X-SCID