Bare lymphocyte syndrome (BLS) is a rare disease characterized by a severe reduction in the cell surface expression of HLA molecules (HLA class I, type I BLS; HLA class II, type II BLS). Patients with BLS-I present with bronchiectasias and skin ulcers associated with granulomatous inflammation.1,2 Synthesis of HLA class I molecules includes transportation of cytoplasmic peptides into the endoplasmic reticulum by the transporter-associated antigen-processing (TAP) heterodimers (TAP1 and TAP2). Peptide-loaded HLA class I molecules may interact with cytotoxic CD8+ T cells, natural killer (NK) cells, and γδ T cells.3 Patients with BLS-I, who have a defective TAP complex, may have 1 of 4 different mutations. Tissue typing and molecular analysis of 15 patients demonstrated that they were homozygous for a defective TAP1 or TAP2 mutation.4