ATIs develop in 8-60% of IBD patients1. Fully-humanized antibodies such as adalimumab and golimumab induce similar rates of immunogenicity, suggesting post-translational modifications as possible antigenic epitopes2. One consideration is sialylation, the addition of terminal N-acetylneuraminic acid (NANA) or N-glycolylneuraminic acid (NGNA) to N-linked glycosylations. Humans are unable to produce NGNA from the precursor NANA due to a single enzyme mutation3. Therefore, presence of NGNA on infliximab may induce ATI formation.