ATG16L1 and inflammatory bowel disease: IBD candidate risk loci, in particular those with mutations in the CARD15 gene, encoding the bacterial-sensing protein NOD2, have been associated with reduced α-defensin production (i.e., DEFA5 and DEFA6) in both adult and pediatric ileal patients with CD [13,14].Also the CD risk allele ATG16L1 predisposes Paneth cells to lose their ability to form normal intracellular granules [15], resulting in a lower production of antimicrobial peptides [16].