A severe combined immunodeficiency that has_material_basis_in autosomal recessive mutations in the gene coding for T-cell surface glycoprotein CD3gamma chain precursors. Patients with CD3gamma deficiency have a severe defect in the expression of the T-cell receptor CD3-complex. Affected patients have decreased T-cell numbers and function; B cells are variably affected. [ http://purl.obolibrary.org/obo/ECO_0007645 ]