Thus, HIV-negative patients with underlying disease, such as cancer, mixed connective tissue disease, transplant rejection, systemic lupus erythematosus, diabetes mellitus, and Langerhans cell histiocytosis, and those taking corticosteroids or immunosuppressive agents, exhibited worse CD4 T-cellular immunodeficiency during the course of the disease than HIV-negative patients without underlying disease. This evidence concerns the gene CD4 and mixed connective tissue disease.