In this context, we identified T and B lymphopenia, a reduction in CD4+ and CD8+ naїve T‐cells%, T‐reg cells% and switched memory B‐cells%, and an increase in CD4+ effector memory T‐cells% and CD21low B‐cells% along with the presence of hypogammaglobulinemia as variables significantly associated with IEI. The gene discussed is CD4; the disease is agammaglobulinemia.