A notable finding was the almost complete absence of immunoglobulins (IgG levels undetectable or below 12 mg/dL, along with rather undetectable IgM and IgA levels, namely a presence of agammaglobulinemia) in the peripheral blood of 9 PAD patients (5.9%); among them, 8 patients belonged to Group A and 1 patient to Group B. This evidence concerns the gene CD40LG and peripheral arterial disease.