Histocompatibility antigens and other genetic markers in ankylosing spondylitis and inflammatory bowel diseases.

Of 118 Dutch patients suffering from ankylosing spondylitis (AS) 81-4% were found to be positive for the HLA antigen B27. The B27 frequency proved to be significantly higher in patients in whom the disease had an early onset. In addition to B27, another HLA antigen may be associated with AS; the antigen Bw 16 was found to be significantly increased in B27 negative AS patients. HLA phenotype frequencies were also determined in 109 patients with idiopathic inflammatory bwel disease (IBD). In fifty-eight ulcerative colitis (UC) patients a raised incidence of A 11 was noticed. In fifty-one patients with Crohn's disease (CD) the antigen B18 showed an increased frequency. Both deviations were statistically significant. In thirty-nine patients suffering from both AS and IBD 50% proved to be B27 positive, which is significantly diffrent from B27 frequency in patients with AS alone. In the B27 negative patients with AS and IBD and increased frequency of Bw16 was also shown.