Recent epidemiological, clinical and molecular studies have provided strong
evidence that inherited predisposition is important in the pathogenesis of
chronic inflammatory bowel diseases. The model most consistent with the ep
idemiological data suggests that Crohn's disease and ulcerative colitis are
related polygenic diseases, sharing some but not all susceptibility genes.
Investigators throughout the world have applied the complementary techniqu
es of genome-wide scanning and candidate gene analysis. Four areas of linka
ge have been widely replicated on chromosomes 16 (IBD1), 12 (IBD2), 6 (IBD3
-the HLA region), and most recently on chromosome 14. Fine mapping of these
regions is underway. Of the 'positional' candidate genes, most attention h
as centred on the genes of the major histocompatibility complex. Genes with
in this region may determine disease susceptibility, behaviour, complicatio
ns and response to therapy. Hope continues that studies of inflammatory bow
el disease genetics will provide fresh insight into disease pathogenesis an
d soon deliver clinical applications.