title: Ankylosing Spondylitis: HLA-B*27-Positive Versus HLA-B*27-Negative Disease.
abstract: OBJECTIVE
  We review our current knowledge about the clinical features of patients with ankylosing spondylitis (AS) who possess HLA-B*27 versus those who lack this gene.
  
  
  RESULTS
  ERAP1 association is present only in HLA-B*27+ patients, but other genetic associations are similar between the two groups. A genetic study supports the existence of an HLA-B27-independent common link between gut inflammation and AS. It is unusual to observe familial occurrence of primary AS among families of northern European extraction that show no segregation of HLA-B*27, psoriasis, or IBD. Although there are many similarities among AS patients possessing HLA-B*27 versus those lacking this gene, the former group has a younger age of onset, a shorter delay in diagnosis, a better clinical response to tumor necrosis factor inhibitors, a greater familial occurrence, a greater risk for occurrence of acute anterior uveitis, and a lower risk for occurrence of psoriasis and IBD. ERAP1 association is present only in HLA-B*27+ patients, but other genetic associations are similar between the two groups. It is unusual to observe occurrence of primary AS among families of northern European extraction that show no segregation of HLA-B*27, IBD, or psoriasis. A recent genetic study supports the existence of an HLA-B*27-independent common link between gut inflammation and AS.
authors.affiliation: , Izmir, Turkey. nurullah.akkoc@gmail.com.
authors.forename: Nurullah
authors.initials: N
authors.lastname: Akkoç
authors.affiliation: Department of Rheumatology, Faculty of Medicine, Dokuz Eylul University, Balcova, 35340, Izmir, Turkey.
authors.forename: Handan
authors.initials: H
authors.lastname: Yarkan
authors.affiliation: Department of Rheumatology, Faculty of Medicine, Dokuz Eylul University, Balcova, 35340, Izmir, Turkey.
authors.forename: Gökçe
authors.initials: G
authors.lastname: Kenar
authors.affiliation: MetroHealth Medical Center, Case Western Reserve University, 2500 MetroHealth Drive, Cleveland, OH, 44109, USA.
authors.forename: Muhammad A
authors.initials: MA
authors.lastname: Khan
mesh_terms: D000626:Aminopeptidases / Q000235:genetics; D020022:Genetic Predisposition to Disease; D015796:HLA-B27 Antigen / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000150:complications / Q000235:genetics; D015778:Minor Histocompatibility Antigens / Q000235:genetics; D011565:Psoriasis / Q000150:complications / Q000235:genetics; D013167:Spondylitis, Ankylosing / Q000150:complications / Q000235:genetics*; D014606:Uveitis, Anterior / Q000150:complications / Q000235:genetics
chemical_list: D015796:HLA-B27 Antigen; D015778:Minor Histocompatibility Antigens; D000626:Aminopeptidases; C464841:ERAP1 protein, human
keywords: Ankylosing spondylitis; Clinical features; ERAP1; Familial occurrence; Genetic susceptibility; HLA-B*27; HLA-B27; Inflammatory bowel disease; Psoriasis; Spondyloarthritis; Uveitis