Anticipation in an Indo-Canadian family with Crohn's disease

Genetic anticipation, associated elsewhere with monogenic neurological diso rders, has been hypothesized to be present in familial forms of Crohn's dis ease. Usually, with studies of parent-child pairs, the parent who is initia lly diagnosed is older at the onset of disease than the child. With each su ccessive generation, an apparent increase in disease severity or behaviour occurs. This phenomenon is believed to have a molecular basis. In the prese nt report, an Indo-Canadian family with Crohn's disease is described. In al l members of the family, disease was diagnosed only after prolonged residen ce in Canada, supporting the view that Crohn's disease arises in individual s with a genetic predisposition following exposure to some, as yet unknown, common environmental factor. Three siblings with Crohn's disease, first di agnosed between ages 15 and 27 years, or six to 11 years after arrival in C anada, had phenotypically concordant disease localized in the ileum and col on, with fistulizing complications, including perianal sepsis. Crohn's dis, ease was only diagnosed in the father at the age of 76 years, almost three decades after his arrival in Canada. His disease was localized to the ileu m and had a fibrostenosing behaviour. This is the first reported instance o f familial Crohn's disease in an immigrant population, illustrating potenti al biases in genetically based studies of Crohn's disease that rely solely on phenotypic expression.