Test Details: Anti-Saccharomyces cerevisiae antibodies (ASCAs) are antibodies against antigens presented by the cell wall of the yeast Saccharomyces cerevisiae. ASCA antibodies react to a yeast protein with a 200-kDa glycoprotein called mannan and are frequently present in people who have inflammatory bowel disease (IBD) and also help to distinguish between Crohn disease (CD) and ulcerative colitis (UC). ASCA tends to recognize Crohn's disease more frequently, whereas pANCA tend to recognize ulcerative colitis. Testing usually includes detecting IgA antibody.