 Paediatric- onset n75, elderly-onset CD patients n75 and control subjects matched on age, gender and geographical origin urban, periurban and rural area according to INSEE data in each group n150 will be recruited through a large population-based registry of IBD patients EPIMAD Registry. In 2 case-control studies, controls n150 will be matched to cases by age 2 years, gender and geographical origin urban, periurban and rural area according to INSEE data. Control subjects will be recruited through paediatric and geriatric consultations in Lille University Hospital. 