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The molecular classification of the clinical manifestations of Crohn's disease
Tariq Ahmad1, Alessandro Armuzzi, Mike Bunce
1Gastroenterology Unit, University of Oxford, Gibson Laboratories, Radcliffe Infirmary, Oxford, United Kingdom. tariq.ahmad@ndm.ox.ac.uk
Background & Aims:
Crohn's disease is a common inflammatory disorder of the gut characterized by variation in both location and behavior. Chromosome 16 and the HLA region on chromosome 6 have been implicated in susceptibility to disease. Mutations in the NOD2/CARD15 gene, recently identified on chromosome 16, have been associated with disease overall but are found in only 25% of patients. No data regarding their contribution to specific disease subtypes exist. Here we report a detailed genotype-phenotype analysis of 244 accurately characterized patients.
Methods:
A total of 244 white patients with Crohn's disease recruited from a single center in the United Kingdom were studied. All patients were rigorously phenotyped and followed-up for a median time of 16 years. By using linkage disequilibrium mapping we studied 340 polymorphisms in 24 HLA genes and 3 NOD2/CARD15 polymorphisms.
Results:
We show that NOD2/CARD15 mutations determine ileal disease only. We confirm that alleles on specific long-range HLA haplotypes determine overall susceptibility and describe novel genetic associations with susceptibility, location, and behavior of Crohn's disease.
Conclusions:
The clinical pattern of Crohn's disease may be defined by specific genotypes. This study may provide the basis for a future molecular classification of disease.
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