Although it could be argued that generally low antibody levels would be an expected reflection of the deleterious effects of disease on the immune system, a study by Shih et al. found no difference in total serum immunoglobulin (Ig) levels (IgA, IgG and IgM) for lung and breast cancer patients with late-stage disease compared to healthy controls. The gene discussed is CD40LG; the disease is breast cancer.