title: The distribution of HLA-B27 subtype in patients with ankylosing spondylitis in Northern Norway.
abstract: BACKGROUND
  Although the high prevalence of human leucocyte antigen (HLA)-B27 and ankylosing spondylitis (AS) in Northern Norway is now well documented, data on the distribution of HLA-B27 subtypes and their potential impact on disease presentation and course are lacking.
  
  
  METHODS
  We conducted a cross-sectional study of patients (n = 124) with established (modified New York criteria) AS participating in a longitudinal disease registry. Clinical data at the time of sample collection were recorded and genotyping for HLA-B27 was performed by low-resolution polymerase chain reaction (PCR) screening. Subtyping was then performed with sequence-specific primers (PCR-SSP) and direct exon 2 and 3 sequencing. The results were analysed with SCORE and Seqscape software.
  
  
  RESULTS
  Four patients (3%) were HLA-B27 negative in all genetic analyses. In the remaining 120 HLA-B27-positive patients, HLA-B27*05 was present in 117 (98%) and HLA-B27*02 in three patients (2%). There was complete concordance between the screening and subtyping results. The three patients with HLA-B27*02 had no distinguishing clinical characteristics.
  
  
  CONCLUSIONS
  HLA-B27*05 is the predominant subtype of HLA-B27 in Northern Norway. This supports the concept of a North-South gradient for HLA-B27 subtypes with little regional drive to adapt to environmental challenges. Low-resolution HLA-B27 PCR screening captures all relevant subtypes in this region.
authors: Faculty of Health Sciences, Institute of Clinical Medicine, University of Tromsø , Tromsø , Norway.
authors: S S
authors: SS
authors: Johnsen
authors: G
authors: G
authors: Bakland
authors: J C
authors: JC
authors: Nossent
mesh_terms: D003430:Cross-Sectional Studies; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing; D005838:Genotype; D015796:HLA-B27 Antigen / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway; D016133:Polymerase Chain Reaction; D015995:Prevalence; D013167:Spondylitis, Ankylosing / Q000235:genetics*
chemical_list: D015796:HLA-B27 Antigen