Antineutrophil cytoplasmic antibody (ANCA), which is directed against proteinase 3 (PR3), is a marker for granulomatosis with polyangiitis and is also seen in patients with IBD, particularly UC [7]. The serologic markers that have been identified as diagnostic markers for CD include anti-Saccharomyces cerevisiae antibodies (ASCAs), anti-Pseudomonas fluorescens-associated sequence I2 antibodies, anti-Escherichia coli outer membrane porin C antibodies, anti-bacterial flagellin antibodies, and anti-CD peptide antibodies [6]. The gene discussed is PRTN3; the disease is Cowden disease.