[Diagnosis and treatment of adult patients with inborn errors of immunity]

Primary immunodeficiency diseases (PID) are caused by abnormalities in molecules involved in the immune system, and there are nearly 500 genes associated with PID. The symptoms are not only susceptibile to infectious diseases but also to autoimmune diseases, malignancies, autoinflammatory diseases, and allergies. Thus, these diseases are considered inborn errors of immunity (IEI) rather than PID. IEI is typically thought to occur in childhood because IEI is associated with a genetic variant, but there are also several adult-onset IEIs. The same 10 warning signs used to diagnose IEI in children are used to diagnose the condition in adults as well, who are then given a definitive genetic diagnosis after a 4-step diagnostic process. In addition to prophylactic antimicrobial agents and immunoglobulin replacement therapy, allogeneic hematopoietic cell transplantation (HCT) is performed as a curative therapy in some patients with IEI. However, in adult patients with IEI, HCT may have to be stopped due to complications. Adult patients with IEI need to be promptly assessed for HCT, and HCT must be done before complications increase.