severe combined immunodeficiency disease - 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 lifeimmunodeficiency - immunological disorder in which some part of the body's immune system is inadequate and resistance to infectious diseases is reduced ADA-SCID - SCID resulting from mutation of a gene that codes for adenosine deaminase X-linked SCID, X-SCID - SCID in male children resulting from mutation of a gene that codes for a protein on the surface of T cells that allows them to develop a growth factor receptor |