The strongest risk factor for developing inflammatory bowel disease (IBD) is having a relative with the disease. Familial IBD may be one homogeneous subgroup, phenotypically different from sporadic IBD. Several observations support a role for familiarity in disease site and behavior, particularly in Crohn's disease (CD), but published findings do not all concur. Early disease onset is often found in children with TBD who have a parent with the disease. Genetic anticipation may explain this finding but other explanations and/or observational biasis are more likely. Location and type may differ between familial and sporadic CD cases: family studies report many cases involving both small bowel and colon, and few cases of colonic disease alone, although such features may be secondary to early age at onset. Most studies found no effect of positive family history on severity and course of CD. In ulcerative colitis (UC), phenotypic differences between familial and sporadic cases appear to be limited, but little data are available for analysis. No difference has been found between familial and sporadic TBD as far as disease markers such as pANCA, ASCA, or intestinal permeability are concerned. In conclusion, the only message available for clinical practice is that the relative risk of IBD in first-degree relatives is increased by a factor of 10-15 compared with the general population. Families should not receive genetic counselinghformation about agc at onset and disease severity.
Accumulated evidence has shown that inflammatory bowel disease (IBD) may represent a syndrome with multiple etiologies. An etiological classification based on environmental factors and/or genetic traits has not yet been established. Defining homogeneous clinical subgroups may help to identify the causes of IBD and to refine therapeutic approaches. The basic phenotypic classification of Crohn's disease (CD), which was recently revisited (l), only retained age at diagnosis, diseace location, and behavior as major criteria. The strongest risk factor for TBD is having a relative with the disease. Firstdegree relatives of patients with CD have a 12-to-15times greater risk of developing CD than do people of comparable age in the general population.
Recent series have suggested that familial IBD may be