Mixed immunodeficiency diseases are intrinsic defects of the immune system affecting both B and T cells and thus the adaptive immune system. Mixed or combined immune deficiencies may also be associated with or secondary to other diseases. Patients have severe symptoms and the condition can be fatal unless properly treated. Early and reliable diagnosis is in many instances crucial for the efficient treatment of these diseases since delayed diagnosis and management can cause severe and irreversible complications, even the death of the patient. Combined immunodeficiencies, which are a heterogeneous disease group, appear throughout the immune system and affect several crucial genes and proteins. The symptoms and signs vary significantly between the different forms of combined immunodeficiencies.
Key Concepts:
- Combined immunodeficiency affects both B and T cells.
- Lymphocytes are white blood cells including B and T cells.
- Haematopoietic stem cell transplantation, the intravenous infusion of autologous or allogeneic stem cells collected from bone marrow, peripheral blood or umbilical cord blood, reestablishes haematopoietic function in patients.
- V(D)J recombination is genetic recombination which randomly selects and assembles segments of genes encoding specific proteins in the immune system.
Keywords: adaptive immunity; immunodeficiency; immune system; B cell; T cell; severe combined immune deficiency






