APDS, or activated PI3K delta syndrome, is a rare primary immunodeficiency that affects approximately 1 to 2 people per million. It occurs when there are variations to the PIK3CD or PIK3R1 genes.
While people with APDS may suffer from a wide variety of symptoms, the most common are frequent and severe infections of the ears, sinuses, and upper and lower respiratory tracts. Infections usually begin in infancy. People with APDS are susceptible to swollen lymph nodes or an enlarged spleen (splenomegaly), as well as autoimmunity and inflammatory symptoms. People with APDS may be at higher risk for cancers like lymphoma.
See the below diagram for more information about some typical APDS symptoms.