Genetic analysis through WES identified two patients with heterozygous GOF mutations in PIK3CD. Both patients presented with APDS symptoms (i.e., sinopulmonary infections, lymphoproliferation, enteropathy, and autoimmune hemolytic anemia), and displayed a characteristic immune profile including increased proportion of transitional B cells, reduced memory B cells, decreased naïve T cells, and elevated levels of serum IgM (53, 54). The gene discussed is CD40LG; the disease is activated PI3K-delta syndrome.