CD40LG and agammaglobulinemia: Affected individuals present with recurrent respiratory infections, poor immune responses to vaccines, hypogammaglobulinemia with occasional increased levels of serum IgM, susceptibility to viral infections, lymphadenopathy, autoimmunity, and B cell malignancy (Angulo et al., 2013; Deau et al., 2014; Lucas et al., 2014a; Lucas et al., 2014b; Tangye et al., 2019).