ANTICIPATION IN FAMILIAL CROHNS-DISEASE

Background-Offspring with a family history of Crohn's disease have an earlier age of onset than their parents. This might be due to genetic anticipation, characterised by earlier and/or more severe disease in s ubsequent generations. Aims-To investigate the possibility of genetic anticipation in affected parent-child pairs with Crohn's disease from France and Belgium. Patients and methods-In a cohort of 160 multiply a ffected families with Crohn's disease, 57 parent-first affected child pairs were detected. Clinical characteristics (age at diagnosis, disea se extent, and type) of both parents and children were registered and compared. Results-Children were younger than their parents at diagnosi s in 48/57 (84%) pairs. The median age at diagnosis was 16 years young er in children than in parents (P<0.0001). However, the difference was related to the age at diagnosis in the parents and was not present in 12 parent-child pairs with an early age at diagnosis for the parents. In most cases, disease extent and type were not considered more sever e in children than in parents. Parental sex affected neither age at di agnosis nor extent and type of disease in children. Conclusion-Patient s in the second affected generation acquire their disease at an earlie r time in life in some but not all familial cases of Crohn's disease. Several explanations including genetic anticipation and environmental factors might explain this phenomenon.