Longitudinal concordance for clinical characteristics in a Swedish-Danish twin population with inflammatory bowel disease

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Inflammatory Bowel Diseases

Volume 13, Issue 12 , Pages 1536 - 1544

Original Article

Longitudinal concordance for clinical characteristics in a Swedish-Danish twin population with inflammatory bowel disease

Jonas Halfvarson, MD, PhD 1 *, Tine Jess, MD 2, Lennart Bodin, PhD, 3 4, Gunnar Järnerot, MD, PhD, FRCP 1, Pia Munkholm, MD, DMSci 2, Vibeke Binder, MD, DMSci 2, Curt Tysk, MD, PhD 1 5

1Division of Gastroenterology, Department of Internal Medicine, Örebro University Hospital, Örebro, Sweden2Department of Medical Gastroenterology C, Herlev Hospital, University of Copenhagen, Denmark3Statistical and Epidemiological Unit, Örebro University Hospital, Örebro, Sweden4Department of Statistics, Örebro University, Örebro, Sweden5Department of Clinical Medicine, Örebro University, Örebro, Sweden

email: Jonas Halfvarson (jonas.halfvarson@...)

*Correspondence to Jonas Halfvarson, Division of Gastroenterology, Department of Internal Medicine, Örebro University Hospital, Örebro, Sweden

Keywords

inflammatory bowel disease • genetics • twins • genotype-phenotype • Montreal Classification

Abstract

Background: The genetic influence on disease course in inflammatory bowel disease (IBD) remains unknown. We therefore aimed to study longitudinal concordance for clinical characteristics and longitudinal stability using the Montreal Classification in an IBD twin population.

Methods: A total of 158 twins with ulcerative colitis (UC) (18 belonging to 9 concordant monozygotic pairs) and 141 twins with Crohn's disease (CD) (34 belonging to 17 concordant monozygotic pairs) were enrolled. Medical notes were scrutinized for clinical characteristics at diagnosis and after 10 years. Using the binominal distribution, we tested the hypothesis that clinical characteristics were independent within individuals in disease concordant monozygotic pairs.

Results: In CD, location was identical in 11/17 monozygotic concordant pairs at diagnosis (P = 0.008) and in 11/16 pairs after 10 years (P = 0.02). Behavior at diagnosis was identical in 13/17 pairs (P = 0.03) and in 11/16 pairs after 10 years (P = 0.01). Monozygotic UC twins were concordant (within 5 years) for age at diagnosis (6/9 pairs; P < 0.001) and symptomatic onset (4/9 pairs; P = 0.02) but not for extent of disease at diagnosis or after 10 years. The Montreal Classification did not demonstrate longitudinal stability, either regarding location or behavior of CD or extent of UC.

Conclusions: The high phenotypic concordance, both at diagnosis and longitudinally, in monozygotic twins with CD supports a genetic influence not only on disease occurrence but also on disease course. This contrasts with UC, where the genetic impact appears less. Montreal Classification characteristics changed over time and should be used cautiously.

(Inflamm Bowel Dis 2007)

Received: 4 July 2007; Accepted: 7 July 2007

Digital Object Identifier (DOI)