TAP2 deficiency

HLA class I deficiency, also named type I Bare lymphocyte syndrome (BLS), is revealed when HLA class I molecules on lymphocytes cannot be typed by serological techniques due to a low expression of HLA class I molecules on the plasma membrane. This syndrome is caused by any of several defects that result in the lack of cell surface expression of MHC class I or class I and II. It affects both maturation of T cells in the thymus and peripheral immune reactions. The number of well-documented cases of HLA class I molecule deficiencies with normal expression of class II molecules is low.

Alternative names

HLA class I deficiency

Bare lymphocyte syndrome (BLS) type I


  • Combined B and T cell immunodeficiencies
    • Major histocompatibility complex class I deficiency


Autosomal recessive


#604571 Bare lymphocyte syndrome, type I

*170261 Transporter, ATP-binding cassette, major histocompatibility complex, 2; TAP2


Incidence is not known.