title: The HLA system and the arthropathies associated with psoriasis.
abstract: Histocompatibility typing was carried out in 74 patients with psoriasis and an inflammatory arthropathy. In 40 patients with peripheral arthropathy characterized by distal interphalangeal joint involvement, 13 (32-5%) were HLA-B27 positive, significantly higher than the control frequency (P = 5-8 X 10 (-6). 26 of the 40 patients did not have ankylosing spondylitis or radiological sacroiliitis and 7 were HLA-B27 positive, also significantly higher than in controls (P = 0-0049). All 7 patients with psoriasis and ankylosing spondylitis without peripheral arthropathy were HLA-B27 positive. The 10 patients with ankylosing spindylitis or radiological sacroliitis who were HLA-B27 negative all had peripheral arthropathy. It is suggested that being HLA-B27 positive increases the risk of a psoriatic patient developing both peripheral arthropathy and ankylosing spondylitis. In addition, some of the genes involved in susceptibility to psoriasis also have a role in the pathogenesis of both types of arthropathy. A hypothesis is put forward that some of the genes for psoriasis may be aetiologically important in some HLA-B27 negative patients with ankylosing spondylitis.
mesh_terms: D000328:Adult; D000368:Aged; D001168:Arthritis / Q000000981:diagnostic imaging / Q000235:genetics; D001170:Arthritis, Infectious / Q000276:immunology*; D005260:Female; D006680:HLA Antigens / Q000032:analysis*; D006649:Histocompatibility Antigens / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D011565:Psoriasis / Q000150:complications* / Q000235:genetics / Q000276:immunology; D011859:Radiography; D012446:Sacroiliac Joint / Q000000981:diagnostic imaging; D013167:Spondylitis, Ankylosing / Q000276:immunology
chemical_list: D006680:HLA Antigens; D006649:Histocompatibility Antigens