severe combined immunodeficiency: 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
immunological disorder: a disorder of the immune system
parabolic reflector: a concave reflector used to produce a parallel beam when the source is placed at its focus or to focus an incoming parallel beam