Familial Crohn's disease: a study of 18 families

The high frequency of familial Crohn's disease (CD) suggests a genetic predisposition. The most recent data from epidemiology and molecular biology are consistent with a multifactorial, polygenic inheritance with a possible genetic heterogeneity. The aim of our study was, first to compare familial and sporadic CD on the basis of the type and location of the disease, and age at diagnosis, and second, to evaluate among families, the concordance rate for the type and location of the disease.

18 families with 2 (n = 16) and 3 (n = 2) affected first degree relatives were studied. They were compared to a population of 154 sporadic CD coming from the same gastroenterology unit.

Age at diagnosis was the same in sporadic and familial CD. There was an increased frequency of ileal (p = 0.02), and fibro stenotic (p = 0.005) CD and a decreased frequency of colonic (p = 0.006) and inflammatory (p = 0.02) disease, in familial CD. There was a significant increase in concordance rate for fibrostenotic disease (p < 0.001) and a decrease for inflammatory disease (p < 0.01), among the families. The observed concordance rate for the location of the disease was not significantly different from the expected one. In conclusion, these data suggest that CD may be heterogenous and that different clinical patterns may be determined either by genetic or environmental factors.