[The role of major histocompatibility complex genes in the pathogenesis of chronic inflammatory bowel diseases].

Genetic factors, among which the HLA class II coding genes, are implicated in IBD pathogenesis. When considering the ethnic heterogeneity of the studied population and the IBD clinical heterogeneity, UC appears more dependent to HLA genes than CD. UC and HLA genes: HLA DR 4 gene would protect from UC. HLA DR2 gene, particularly the DRB 1 * 1502 allele, is predisposing for more severe forms necessitating a corticotherapy, while DRB 1 * 0301 allele is associated with less needs for surgery. CD and HLA genes: HLA DR 7 gene and the DRB 3 * 0301 allele predispose to CD, while HLA DR 2 and DR 3 genes may be protective factors. Thus, for MC patient, the DRB 1 * 0301/DQB*0201 haplotype might be associated with less occurrence of fistulas or severe forms requiring immunosuppressive therapy.