Ulcerative colitis and Crohn's disease in an unselected population of monozygotic and dizygotic twins. A study of heritability and the influence of smoking.

• DOI: 10.1136/gut.29.7.990
• Publication Date: 2007-09-18T21:41:31Z
• Authors: C Tysk; E Lindberg; G Jarnerot; B Floderus-Myrhed
• Keywords: Concordance; Monozygotic twin; Dizygotic twins; Zygosity; Heredity

By running the Swedish twin registry containing about 25,000 pairs of twins same sex together with central national diagnosis register hospital inpatients, 80 suffering from inflammatory bowel disease were found. In ulcerative colitis group one 16 monozygotic was concordant for disease, but all other 20 (dizygotic or unknown zygosity) discordant. Crohn's eight 18 and 26 dizygotic concordant. The proband concordance rate among 6.3% 58.3% disease. calculated heritability liability based on 0.53 1.0 respectively. Thus heredity as an aetiological factor is stronger in than colitis. Monozygotic more likely to be smokers Smoking did not explain discordance either colitis, combination identical similar smoking habit sufficient cause