CD40LG and isolated agammaglobulinemia: Additionally, patients may develop comorbid autoimmune disorders, such as myasthenia gravis; (2) a history of thymoma; (3) laboratory examination indices: hypogammaglobulinemia (decreased IgG, IgA, and IgM), decreased or completely lacking B lymphocytes in peripheral blood, reduced NK cell counts, and T lymphocyte dysfunction; and (4) the exclusion of phenocopies such as common variable immunodeficiency (CVID) and X-linked agammaglobulinemia (XLA) is essential, given their similar manifestations of recurrent infections and humoral immune deficiency (2, 13, 14).