Familial expression of anti-Saccharomyces cerevisiae mannan antibodies in Crohn's disease and ulcerative colitis: A GISC study

OBJECTIVES: Recent studies in familial Crohn's disease (CD) have suggested that anti-Saccharomyces cerevisiae mannan antibodies (ASCAs) may represent a new specific marker of genetic susceptibility. In this study we aimed to assess the importance of ASCAs by comparing their presence in a large numbe r of patients with sporadic and familial occurrence of CD or ulcerative col itis (UC) and their unaffected relatives. METHODS: Serum samples from 96 patients with sporadic CD, 97 patients with sporadic UC. and 50 unrelated healthy controls were tested for ASCAs by a s tandard ELISA method. Moreover, 73 families with two or more members affect ed by CD and/or UC were recruited. From these families 58 CD patients, 84 U C patients, and 216 unaffected first degree relatives were investigated. RESULTS: ASCAs were detected in 34 of 96 patients with sporadic CD (35%, p < 0.01 vs controls), I I of 97 patients with sporadic UC (12%), and two of 50 controls (4%). ASCAs were significantly (p < 0.04) more frequent in pati ents with familial CD (55%) and familial UC (25%) than in sporadic cases. M oreover, ASCAs were found in 25% of unaffected relatives, and this rate did not significantly differ in CD, UC, and mixed families (28%, 26%, and 22%, respectively). CONCLUSIONS: In this study we confirm that ASCAs occur particularly frequen tly in CD patients, especially with the presence of a positive family histo ry. However, they are also significantly increased in UC patients with a fa mily history and in a considerable number of unaffected relatives of inflam matory bowel disease families. irrespective of the characteristics of their families (UC, CD, mixed, ASCA positive, and ASCA negative). The presence o f ASCAs in unaffected relatives might point toward a genetic predisposition to either CD or UC. (C) 2001 by Am. Coll. of Gastroenterology.