title: Distribution of HLA class I and II genes in ankylosing spondylitis patients from Morocco.
abstract: OBJECTIVE
  In Morocco, the patients affected by ankylosing spondylitis (AS) presents a high frequency of coxitis. Our study reports, for the first time, the polymorphism of Human Leukocyte Antigen (HLA) class I and class II molecules in the Moroccan patients.
  
  
  METHODS
  Forty-six patients diagnosed with an AS and coxitis were compared to a group of 183 healthy controls matched by age, sex and ethnic origin. The HLA typing was performed using microlymphocytotoxicity for the class I (-A, -B) and PCR-SSP for the class II (-DR, -DQ).
  
  
  RESULTS
  We found a significant increase of the HLA-B27 antigen frequency (P<0.0001, RR=20.9) in AS patients (29.3%) compared to the controls (3.2%) and a significant decrease in the frequency of HLA-B12 and HLA-B18 antigens. Examination of HLA class II distribution shows a significant increase of the HLA-DRB1*11 allele frequency in patients (P<0.0001). Concerning HLA-DQB1* alleles, no significant difference between patients and controls was appreciable.
  
  
  CONCLUSIONS
  The HLA-B27 antigen is involved in the predisposition to the AS with coxitis in the Moroccan population. However, the low frequency observed in our population suggests the existence of other genetic and/or environmental factors. Other HLA genes seem to confer a predisposing effect (DRB*11) or a protective effect (B12 and B18) against the disease.
authors.affiliation: Unité d'immunologie, service de transfusion sanguine et d'hémovigilance, CHU Ibn Sina, Rabat, Morocco. atoufoufa@gmail.com
authors.forename: O
authors.initials: O
authors.lastname: Atouf
authors.forename: K
authors.initials: K
authors.lastname: Benbouazza
authors.forename: C
authors.initials: C
authors.lastname: Brick
authors.forename: B
authors.initials: B
authors.lastname: Saoud
authors.forename: N
authors.initials: N
authors.lastname: Benseffaj
authors.forename: B
authors.initials: B
authors.lastname: Amine
authors.forename: N
authors.initials: N
authors.lastname: Hajjaj-Hassouni
authors.forename: M
authors.initials: M
authors.lastname: Essakalli
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D006680:HLA Antigens / Q000145:classification / Q000235:genetics; D015235:HLA-B Antigens / Q000235:genetics; D059911:HLA-B18 Antigen / Q000235:genetics; D059866:HLA-DQ beta-Chains / Q000235:genetics; D059811:HLA-DRB1 Chains / Q000235:genetics; D015395:Histocompatibility Antigens Class I / Q000235:genetics; D000949:Histocompatibility Antigens Class II / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009018:Morocco; D011110:Polymorphism, Genetic; D013167:Spondylitis, Ankylosing / Q000235:genetics* / Q000276:immunology*
chemical_list: D006680:HLA Antigens; D015235:HLA-B Antigens; C035015:HLA-B12 antigen; D059911:HLA-B18 Antigen; D059866:HLA-DQ beta-Chains; C069051:HLA-DQB1 antigen; D059811:HLA-DRB1 Chains; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II