[The forefront of primary immunodeficiencies].

Primary immunodeficiencies (PIDs) are inherited disorders caused by an impaired immune system. Because the immune system effects various immune reactions, PIDs present various clinical phenotypes including increased susceptibility to infections, autoimmunity, and malignancies. For adequate diagnosis of PIDs, a systematic approach using clinical genetic sequencing is required. New technologies including next-generation sequencing have become widely available and have led to the identification of novel genetic defects underlying PIDs. In the clinical setting, the identification of genes responsible for impaired immune system function for each PID enables the proposition of more disease-specific treatment options that target the affected signaling pathway. Research on PIDs not only benefits clinical treatment, it also provides a deeper understanding of the human immune system.