Striking prevalence of ankylosing spondylitis in "healthy" w27 positive males and females

N Engl J Med. 1975 Oct 23;293(17):835-9. doi: 10.1056/NEJM197510232931701.


Ankylosing spondylitis is diagnosed once or twice in each 1000 males and one tenth as frequently in females, but the true prevalence is unknown. Indentification of genetic marker, HL-A W27, for susceptible persons has provided a tool facilitating epidemiologic studies and allowing identification of "control" populations without the marker. Evaluation by postal questionnaires, and pelvic radiography of 78 HL-A 27W-positive blood donors selected from a group of apparently healthy subjects revealed 14 who satisfied the criteria for definite ankylosing spondylitis. The prevalence was similar in both sexes. One hundred and twenty-six W27-negative controls matched for race, sex, and age failed to yield a single case. For a person of either sex with HL-A W27, there appears to be about a 20 per cent chance that ankylosing spondylitis will develop, suggesting a prevalence of 10 to 15 per thousand. Hitherto accepted figures may underestimate the frequency by a factor of 10 to 20.

MeSH terms

  • Adult
  • Aged
  • Back Pain / epidemiology
  • Blood Donors
  • California
  • Female
  • HLA Antigens / analysis*
  • Histocompatibility Antigens / analysis*
  • Humans
  • Male
  • Middle Aged
  • Radiography
  • Sacroiliac Joint / diagnostic imaging
  • Spondylitis, Ankylosing / diagnosis
  • Spondylitis, Ankylosing / epidemiology*
  • Spondylitis, Ankylosing / genetics
  • Spondylitis, Ankylosing / immunology


  • HLA Antigens
  • Histocompatibility Antigens