Chronic necrotizing granulomatous skin lesions and MHC class I deficiency syndrome due to TAP2 deficiency

Major histocompatibility complexes class I (MHC- I) deficiency, also known as bare lymphocyte syndrome type 1 (BLS-1), is a rare autosomal recessively inherited immunodeficiency disorder with remarkable clinical and biological heterogeneity. Transporter associated with antigen processing (TAP) is a member of the ATP-binding cassette superfamily of transporters and consists of two subunits, TAP1 or TAP2. Any defect resulting from a mutation or deletion of these two subunits, adversely affects the peptide translocation in the endoplasmic reticulum, which is an important process for the proper assembly of MHC- I molecules. To date, few patients with reduced cell surface expression of MHC-I molecules have been reported. Herein; we described two Iranian cases with 2 and 3 decades delayed diagnosis of chronic necrotizing granulomatous skin lesions due to TAP2 deficiency without pulmonary involvement; and then segregation analysis in family members was performed by PCR and Sanger sequencing among 10 members of their family and found three homozygous mutation in three asymptomatic patients.