Bare Lymphocyte Syndromes (BLS) refer to a group of rare genetic disorders characterized by abnormalities in the development and function of lymphocytes, which are a type of white blood cells responsible for immune system function. These syndromes are primarily inherited as autosomal recessive traits, meaning that an affected individual must inherit a faulty gene from both parents to develop the condition.
In BLS, the affected individuals have deficiencies in major histocompatibility complex (MHC) class I or class II molecules, which are responsible for presenting antigens to the immune system and facilitating appropriate immune responses. As a result, the immune system is compromised, leading to increased susceptibility to various infections.
Bare Lymphocyte Syndromes are classified into two types: Bare Lymphocyte Syndrome type I (BLS I) and Bare Lymphocyte Syndrome type II (BLS II). BLS I is caused by mutations in the TAP1 or TAP2 genes, which are involved in the transport of antigens into the endoplasmic reticulum for MHC class I presentation. BLS II is caused by mutations in the RFXANK, RFX5, or RFXAP genes, which are involved in the activation and assembly of the transcription factor complex required for MHC class II expression.
Symptoms of BLS can vary, but commonly include recurrent infections, particularly viral, bacterial, and fungal, as well as autoimmune conditions. The diagnosis of BLS is usually confirmed through genetic testing and evaluation of immune system function.
Treatment for BLS primarily focuses on managing and preventing infections by administering prophylactic antibiotics and immunoglobulin replacement therapy. In severe cases, bone marrow or hematopoietic stem cell transplantation may be considered. Genetic counseling is recommended for individuals with
