Multiple studies, including those by Warnatz, Piqueras, and the EUROclass group, consistently demonstrated that a marked reduction in switched memory B cells (CD27+IgM−IgD−) in CVID patients is associated with immune dysregulation features such as splenomegaly, lymphadenopathy, and AICs [33–35]. This evidence concerns the gene CD27 and Splenomegaly.