HLA-DR covers Bare Lymphocyte Syndrome.

Abstract

Major Histocompatibility Complex (MHC) Class II deficiency also called Bare Lymphocyte Syndrome (BLS) is a combined primary immunodeficiency causing an impairment of both the cellular and humoral immune responses1 . This autosomal recessive disorder is characterized by absent Human Leukocyte Antigen - DR (HLA-DR) expression on immune cells resulting from a defect in genes encoding one or more of the 4 distinct regulatory proteins required for MHC Class II genes expression namely class II trans activator (CIITA) under group A , RFX containing ankyrin repeats (RFXANK) under group B , the fifth member of the RFX (RFX5) under group C , and RFX-associated protein (RFXAP) under group D. Patients may have varied clinical presentation, however, severe infections of the respiratory and gastrointestinal tracts in the first year of life itself are common.