Inborn Errors of Immunity in Apoptosis.

Inborn errors of immunity (IEIs) are a group of more than 485 disorders that impair immune development and function with variable reported incidence, severity, and clinical phenotypes. A subset of IEIs blend increased susceptibility to infection, autoimmunity, and malignancy and are known collectively as primary immune regulatory disorders (PIRDs). Programmed cell death, or apoptosis, is crucial for maintaining the balance of lymphocytes. Genetic-level identification of several human inherited diseases with impaired apoptosis has been achieved, such as autoimmune lymphoproliferative syndrome (ALPS), caspase-8 deficiency state (CEDS), X-linked lymphoproliferative syndrome (XLP), and Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway disorders. The consequences of this disease are manifested by abnormal lymphocyte accumulation, resulting in clinical features such as lymphadenopathy, hepatomegaly, splenomegaly, and an increased risk of lymphoma. Additionally, these disorders are often associated with autoimmune disease, particularly involving blood cells. Understanding the molecular pathogenesis of these conditions has provided critical insights into the signaling pathways that regulate apoptosis and lymphocyte activation, shedding light on mechanisms of immune dysregulation. This review focuses on the intersection between apoptosis, autoimmunity, and lymphoproliferation, discussing how dysregulation contributes to the development of these immune disorders. These conditions are characterized by excessive lymphocyte accumulation, autoimmunity, and/or immunodeficiency. Understanding their molecular pathogenesis has offered new insights into the signaling mechanisms that regulate apoptosis and lymphocyte activation.