Antineutrophil antibodies in familial inflammatory bowel disease

Antineutrophil cytoplasmic antibodies have been reported to occur more frequently in healthy first-degree relatives of patients with ulcerative colitis than in healthy controls. The aim of this study was to determine their prevalence in families in which more than one member was affected with inflammatory bowel disease.

With use of an indirect immunofluorescence method, 168 affected members and 197 unaffected first-degree relatives in 56 such families were studied.

Antibodies were detected in 46% of patients with ulcerative colitis without a positive family history and in 44% of those within families with several affected members. There was no evidence of clustering of antibodies in particular families. Within families in which both ulcerative colitis and Crohn's disease coexisted, antibodies were detected primarily in patients with ulcerative colitis. Antibodies were seldom present (3%) in those patients with Crohn's disease, whether they were familial or nonfamilial cases. Similarly, antibodies were seldom present (3%) in controls or the unaffected first-degree relatives of patients with inflammatory bowel disease.

Antineutrophil cytoplasmic antibodies are associated with ulcerative colitis, and their presence is not increased in the first-degree relatives of patients with ulcerative colitis. They are more likely to be a consequence of the disease than a subclinical genetic disease marker.