title: Distribution of HLA-B*27 subtypes in Tunisians and their association with ankylosing spondylitis.
abstract: OBJECTIVE
  The human leukocyte antigen HLA-B27 is a class I antigen of the major histocompatibility complex strongly associated with ankylosing spondylitis (AS) and other related spondyloarthropathies (SpAs). The mechanism of this association remains unknown. HLA-B27 is a serologic specificity that represents a family of at least 25 different HLA-B27 alleles (2701-2725). These alleles are closely related by nucleotide sequence homology, but differ in ethnic distribution. The purpose of the present study is to investigate the distribution of HLA-B27 alleles in healthy controls and in patients with ankylosing spondylitis (AS).
  
  
  METHODS
  We selected 160 HLA-B27-positive individuals (39 controls and 121 patients with ankylosing spondylitis). Typing of HLA-B27, and Cw alleles were performed by polymerase chain reaction amplification with sequence specific primers (PCR-SSP), and by serological typing (microlymphocytotoxicity).
  
  
  RESULTS
  Seven B27 subtypes were identified: B*2702, 03, 04, 05, 07, 09 and B*2714. The distribution of these alleles in the population of patients was B*2702 (47.1%) and B*2705 (47.1%). These subtypes were also detected in 16 (41%) and 16 (41%), respectively of the 39 control subjects. HLA-B*2707 was detected in 4 (3.31%) patients and in 3 (7.6%) controls. B*2704, 09 and B*2714 were relatively rare and were detected in one subject each. No significant differences were noticed in the frequencies and distribution of HLA-B27 alleles between patients and controls.
  
  
  CONCLUSIONS
  Our results show a restricted number of HLA B27 subtypes associated with AS. B*2702 and B*2705 were equally common in patients and controls. The most prominent B27/Cw haplotypes in the patient groups and controls were B*2702/Cw02022 and B*2705/Cw02022.
authors.affiliation: Department of Immunology, EPS Charles Nicolle, Boulevard 9 Avril, 1006 Tunis, Tunisia.
authors.forename: Karima
authors.initials: K
authors.lastname: Ben Radhia
authors.forename: Saloua
authors.initials: S
authors.lastname: Ayed-Jendoubi
authors.forename: Imene
authors.initials: I
authors.lastname: Sfar
authors.forename: Thouraya
authors.initials: T
authors.lastname: Ben Romdhane
authors.forename: Mouna
authors.initials: M
authors.lastname: Makhlouf
authors.forename: Yousr
authors.initials: Y
authors.lastname: Gorgi
authors.forename: Khaled
authors.initials: K
authors.lastname: Ayed
mesh_terms: D000328:Adult; D000483:Alleles; D016022:Case-Control Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D015235:HLA-B Antigens / Q000235:genetics; D015796:HLA-B27 Antigen / Q000235:genetics*; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic / Q000235:genetics*; D013167:Spondylitis, Ankylosing / Q000208:ethnology / Q000235:genetics* / Q000276:immunology; D014416:Tunisia
chemical_list: D015235:HLA-B Antigens; C464936:HLA-B*27:05 antigen; D015796:HLA-B27 Antigen