Studies [23, 24] in recent years have indicated that a reduction in serum Ig levels is common in adults and children with IBD, with one report [23] showing low IgG, IgG1, IgA, and IgM levels in 22.7, 23.4, 7.9, and 10.9% of IBD patients, respectively. This evidence concerns the gene CD40LG and inflammatory bowel disease.