W1251 Epigenetic Variation of Dnmt3l in Paediatric Ileal Crohn's Disease

smokers), and 6 of nine pairs were concordant for severity of disease. Of the five dizygotic twins with CD, disease location and behaviour were also identical in all twin pairs. In nine monozygotic twins with UC (4 females; 5 males), there was good agreement for the use of thiopurine (kappa 0.73; 95%CI 0.10, 1.00) and disease extent (5 total colitis; 1 distal colitis; 1 proctitis) (κappa 0.60; 95% CI 0.13, 1.00). Agreement was poor for disease severity, smoking status, need for steroids and extraintestinal symptoms in UC twins. UC twins were diagnosed at (mean±SEM) 5±1 years of each other. There was no concordance for colectomy in UC twins (2 patients out of 9 UC twin pairs). The majority of concordant IBD twins shared same bedrooms and attended the same school up to a median age of 17 years (range 9-24). CONCLUSION: Our findings suggest that age of disease onset, disease location and disease behaviour in CD, and disease extent in UC, but not extraintestinal manifestations, appeared to be strongly genetically-influenced.