The involvement of HLA -DRB1*, DQA1*, DQB1* and complement C4A loci in diagnosing systemic lupus erythematosus among Tunisians.
BACKGROUND
Genetic susceptibility to systemic lupus erythematosus (SLE) varies among populations. Few data exist on associations of HLA class II and class III alleles of the major histocompatibility complex (MHC) and susceptibility to SLE in Tunisians.


METHODS
We compared HLA-DRB1*, DQA1, DQB1* and C4 allotypes in 62 Tunisian SLE patients and 100 matched controls. We also assessed the association of specific alleles with distinct autoantibody profiles in SLE patients.


RESULTS
HLA-DRB1*0301, -DRB1*1501 and C4AQO alleles were increased in the SLE patients, while the frequencies of HLA-DRB1*04 and DQB1*03 were decreased. HLA-DQA1*0102 and DQA1*0501 were significantly increased in the SLE patients. HLA-DQB1*0201 and DQB1*0602 were more frequent in the SLE patients. C4A*QO and C4B*QO were increased in frequency in the SLE patients compared to the controls, but only C4A null was significantly increased. Eleven of 17 SLE patients with the C4 null allele were HLA-DRB1*0301 positive. Three of 16 SLE patients with HLA-DRB1*1501 were associated with HLA-DQB1*0501 rather than DQB1*0602, as has been reported in European SLE patients.


CONCLUSIONS
The MHC class II alleles (DRB1, DQA1, DQB1) and C4 null associations noted in other ethnic groups are also found in Tunisians, suggesting shared susceptibility factors across ethnic lines in predisposition to SLE. In contrast to other ethnic groups, MHC class II alleles are not associated with the presence of specific autoantibodies in Tunisian SLE patients.
Department of Immunology, Faculty of Medicine and Laboratory of Immunology, Charles Nicolle Hospital, Tunis, Tunisia. khaled.ayed@rns.tn
Khaled
K
Ayed
Yousr
Y
Gorgi
Saloua
S
Ayed-Jendoubi
Rafika
R
Bardi
D016022:Case-Control Studies; D015934:Complement C4a / Q000032:analysis*; D005260:Female; D006683:HLA-DQ Antigens / Q000097:blood*; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains; D006684:HLA-DR Antigens / Q000097:blood*; D059811:HLA-DRB1 Chains; D006801:Humans; D007126:Immunoglobulin Allotypes; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology*; D008297:Male; D010641:Phenotype; D012016:Reference Values; D014416:Tunisia / Q000453:epidemiology
D006683:HLA-DQ Antigens; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains; C069050:HLA-DQA1 antigen; C069051:HLA-DQB1 antigen; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; C553502:HLA-DRB1*03:01 antigen; D007126:Immunoglobulin Allotypes; D015934:Complement C4a