Among PAD patients, Common Variable Immunodeficiency (CVID) was the diagnosis in 75/102 patients (of which 54/75 and 21/75 showed combined IgG, IgA and IgM or IgG and IgA reduction, respectively), 5/102 had isolated IgG subclass deficiency, 2/102 had IgA with IgG subclass deficiency, 1 patient had specific deficit of anti-pneumococcal Ig (SPAD), 17/102 had unclassified antibody deficiency (UAD), whereas 2/102 had agammaglobulinemia. The gene discussed is CD40LG; the disease is peripheral arterial disease.