Identification of mutated PIK3R1 in the proband informed the therapeutic approach for this case; in addition to antibiotic prophylaxis, hydroxychloroquine, intermittent corticosteroids, and immunoglobin replacement therapy, sirolimus was added in an attempt to reduce PI3K activation via inhibition of the mammalian target of rapamycin complex (mTORC; Figure 3), although the published evidence for efficacy in ADPS2 for this approach is sparse, with an ongoing guarded prognosis for lymphoma (8). The gene discussed is PIK3R1; the disease is lymphoma.