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OP002 UK IBD twin and multiplex registry: Concordance and environmental risk factors of twins with IBD

H. Gordon*1, T. Orchard2, A. Steel1, M. Harbord1

1Chelsea and Westminster Hospital, Gastroenterology, London, United Kingdom, 2St Mary's Hospital, Gastroenterology, London, United Kingdom


The UK IBD Twin and Mutliplex Registry is a research database established in October 2013; this study reviews concordance and environmental risk factors of twins recruited. Previous twin studies show concordance in monozygotic (MZ) twins with CD and UC to be 20-55% and 6.3-17%. Dizygotic (DZ) concordance is 0-3.6% (CD) and 0-6.3% (UC) [1] .


Subjects were recruited via IBD charities, retracing members of a dormant database and clinician referral. Adult twin pairs discordant and concordant for IBD were recruited. Participants completed a questionnaire regarding disease history and environmental exposure. Medical records were reviewed when available.


Results: Demographics, Concordance and Zygosity: 100 twin pairs were recruited. Mean age 57 years 5 months, range 21-83 years. 31 MZ:69 DZ. Ratio CD:UC = 48:52. Concordance of twin pairs classified by zygosity and disease type is outlined in table 1.

Early Environment: Higher rates of exclusive breastfeeding were reported in concordant pairs (27.3% n=22 pairs vs 16.7% n=78 pairs). Self reports of perceived childhood illness did not show any difference between IBD and healthy twins of discordant pairs (16.7%, 13/78 vs 19.2%, 15/78). However, the IBD twin more often recalled frequent gastrointestinal infection (10.3%, 8/78 vs 3.8%, 3/78).

Concordance of twin pairs classified by zygosity and disease type.

Crohn’s DiseaseUlcerative Colitis


Diet: IBD twins of discordant pairs had higher rates of consuming "ready made" meals at least weekly before disease onset (12.8%, 10/78 vs 5.1%, 4/78).

Smoking: On review of discordant twin pairs (n=72), there was no significant difference in numbers of current, ex and non smokers between subjects with UC (n=41), CD (n=32) and their healthy twin at time of symptom onset.

Medication and Stress: On review of all IBD sufferers, 7.1% (8/112) and 13.4% (15/112) used NSAIDS and antibiotics within 3 months preceding onset. 48.2% (54/112) reported significant stress within the year before diagnosis.

Time of onset in concordant pairs: The mean lag between diagnosis of concordant pairs was 7 years 5 months.


Concordance of twin pairs with CD is in keeping with the literature. UC concordance is greater than previously quoted. However DZ and MZ concordance of UC twins is similar inferring low heritability. DZ UC pair concordance is 4 fold expected non twin sibling concordance [2], suggesting early environment to be important. This study supports an associaton between diet, stress and gastrointestinal infection with IBD onset. The lack of associatoin with smoking at incidence may reflect sample size.


[1] Brant S, (2012), Update on the heritability of IBD: The importance of Twin Studies. , IBD

[2] Bodger et al, (2010), Concordance for IBD among twins compared to ordinary siblings - a Nowegian population based study., JCC