T-lymphocyte deficiency in Down syndrome.
D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000276:immunology*; D006801:Humans; D007158:Immunologic Techniques; D007223:Infant; D008231:Lymphopenia / Q000209:etiology*; D013601:T-Lymphocytes / Q000276:immunology*