title: Association ofERAP1,IL23RandPTGER4Polymorphisms with Radiographic Severity of Ankylosing Spondylitis.
abstract: BACKGROUND
  Radiographic severity of ankylosing spondylitis (AS) shows such great variance that some patients never develop syndesmophytes throughout the entire disease span, whereas some develop bamboo spine relatively early.
  
  
  OBJECTIVE
  To study the association betweenERAP1,IL23RandPTGER4single nucleotide polymorphisms (SNPs) and radiographic severity in AS patients.
  
  
  METHODS
  rs27044 and rs30187 (ERAP1), rs11209032 (IL23R) and rs10440635 (PTGER4) SNPs were genotyped in 235 AS patients fulfilling the modified New York criteria. Patients were classified as mild- and severe-AS according to modified Stoke AS spinal score (mSASSS). Mild-AS is defined as having mSASSS of "0" following at least 10 years of disease duration. Severe-AS is defined as having mSASSS of >20 (patients with mild vertebral changes (i.e.squaring or erosions) were omitted for clear stratification) regardless of disease duration.
  
  
  RESULTS
  The genotype distributions and allele frequencies ofERAP1rs27044 and rs30187,IL23Rrs11209032 andPTGER4rs10440635 SNPs were similar in mild- (n=171, mSASSS=0, 55.6% HLA-B27 positive) and severe-AS patients (n=64, mSASSS=48.5±17.8, 73.4% HLA-B27 positive). After adjustment for clinical differences between groups (gender, disease duration, HLA-B27 and smoking status) by logistic regression analysis, none of the alleles in the investigated SNPs were found to be associated with radiographic severity of AS.
  
  
  CONCLUSIONS
  In radiographically well-categorized AS patients,ERAP1rs27044 and rs30187,IL23Rrs11209032 andPTGER4rs10440635 SNPs are not found to be associated with radiographic severity of AS.
authors.affiliation: Department of Rheumatology, Faculty of Medicine, Marmara University, Istanbul, Turkey.
authors.forename: Gulsen
authors.initials: G
authors.lastname: Ozen
authors.affiliation: Department of Internal Medicine, Faculty of Medicine, Marmara University, Istanbul, Turkey.
authors.forename: Rabia
authors.initials: R
authors.lastname: Deniz
authors.affiliation: Department of Medical Biology, Faculty of Medicine, Marmara University, Istanbul, Turkey.
authors.forename: Fatih
authors.initials: F
authors.lastname: Eren
authors.affiliation: Department of Medical Biology, Faculty of Medicine, Marmara University, Istanbul, Turkey.
authors.forename: Can
authors.initials: C
authors.lastname: Erzik
authors.affiliation: Department of Rheumatology, Faculty of Medicine, Marmara University, Istanbul, Turkey.
authors.forename: Ali Ugur
authors.initials: AU
authors.lastname: Unal
authors.affiliation: Department of Rheumatology, Faculty of Medicine, Bilim University, Istanbul, Turkey.
authors.forename: Sule
authors.initials: S
authors.lastname: Yavuz
authors.affiliation: Department of Rheumatology, School of Medicine, Ottawa University, Ottawa, Ontario, Canada.
authors.forename: Sibel Zehra
authors.initials: SZ
authors.lastname: Aydin
authors.affiliation: Department of Rheumatology, Faculty of Medicine, Marmara University, Istanbul, Turkey.
authors.forename: Nevsun
authors.initials: N
authors.lastname: Inanc
authors.affiliation: Department of Rheumatology, Faculty of Medicine, Marmara University, Istanbul, Turkey.
authors.forename: Haner
authors.initials: H
authors.lastname: Direskeneli
authors.affiliation: Department of Rheumatology, Faculty of Medicine, Marmara University, Istanbul, Turkey.
authors.forename: Pamir
authors.initials: P
authors.lastname: Atagunduz
keywords: Ankylosing spondylitis; ERAP1; IL23R; PTGER4; radiographic severity