Bare lymphocyte syndrome (BLS) is a rare recessive genetic immune disorder endorsed by a partial or complete absence of major histocompatibility complex (MHC) or human leukocyte antigen (HLA) expression. BLS could be grouped as type I, type II, and type III based on defective surface MHC expression. A feature of loss in constitutive and inducible MHC II proteins have been grouped as BLS type II. BLS type III is recognized by the loss of both MHC I and MHC II molecules.
