Familial versus sporadic inflammatory bowel disease: The same disease?

The strongest risk factor for developing inflammatory bowel disease (IBD) is having a relative with the disease. Some studies have suggested that familial IBD may be one homogeneous subgroup, phenotypically different from sporadic IBD. If confirmed, this finding could be important for disease modelling and genetic counselling, and it should become easier to assess differences between sporadic and familial cases. Several observations support a role for familiality in disease site and behaviour, particularly in Crohn's disease (CD), but published findings do not all concur. Early disease onset is often found in children with IBD who have a parent with the disease and genetic anticipation may explain this. 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 find 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. In clinical practice, the relative risk of IBD in first-degree relatives is increased by a factor of 10-15 compared to that in the general population. Families should not receive genetic counselling/ information about age at onset and disease severity, and there is no evidence that aetiological factors are different in familial and non-familial IBD.