Group of rare congenital disorders characterized by impairment of both humoral and cell-mediated immunity, leukopenia, and low or absent antibody levels. It is inherited as an X-linked or autosomal recessive defect. Mutations occurring in many different genes cause human Severe Combined Immunodeficiency (SCID).

Synonyms: Bare Lymphocyte Syndromes, Syndrome, Bare Lymphocyte, Severe Combined Immunologic Deficiency, Omenn's Syndrome, Severe Combined Immunodeficiency Syndrome, Syndrome, Omenn's, Syndrome, Omenn, Immunodeficiencies, Severe Combined, Familial Reticuloendothelioses, Combined Immunodeficiency, Severe, Familial Reticuloendotheliosis, Reticuloendotheliosis, Familial, Omenn Syndrome, Reticuloendothelioses, Familial, Lymphocyte Syndrome, Bare, Immunodeficiency, Severe Combined, Lymphocyte Syndromes, Bare, Severe Combined Immunodeficiencies, Immunologic Deficiency, Severe Combined, Severe Combined Immune Deficiency, Combined Immunodeficiencies, Severe, Severe Combined Immunodeficiency, Syndromes, Bare Lymphocyte, Bare Lymphocyte Syndrome, Immunodeficiency Syndrome, Severe Combined, Omenns Syndrome