C1GALT1 and colitis: For example, mice deficient in core 1 synthase, specifically glycoprotein-N-acetylgalactosamine 3-beta-galactosyltransferase 1 (C1galt1), a crucial enzyme in the biosynthesis of core 1 or 2 O-glycans, exhibited a defective mucus layer in the colon, leading to severe colitis resembling that seen in Muc2-deficient mice [32].