PIK3CD and immune system disorder: PIK3CD mutation-related immunodeficiency stems from autosomal dominant inheritance, leads to hyperactivity of the PI3K/Akt/mammalian target of the rapamycin (mTOR) signaling pathway, induces cell differentiation and proliferation, and results in liver, spleen, lymph node enlargement and other manifestations indicating the occurrence of disease (Burke et al., 2011; Angulo et al., 2013; Kang et al., 2020).