IFNL3 and inflammatory bowel disease: More compelling genetic support for a specific role of Type III interferon signaling is a report of 2 patients with very early onset inflammatory bowel disease who were homozygous or compound heterozygous for loss-of-function variants in IFNL2 and IFNL3.31 There is experimental support for a protective role of Type III interferon signaling in inflammatory bowel disease.