RESUMO
OBJECTIVE: To investigate the predisposing role of major histocompatibility complex (MHC) genes to systemic lupus erythematosus (SLE) in a Chinese population. METHODS: Polymorphism in the HLA-DRB, DQB, complement component C4, and 21-hydroxylase genes was analyzed by restriction fragment length polymorphism analysis and oligonucleotide probing of in vitro-amplified DNA from 88 Chinese patients with SLE and 69 matched control subjects. RESULTS: HLA-DRw15 and DQw1 were significantly more frequent in patients (corrected P less than 0.006, relative risk 5.2), but none of the 9 sequence variants of DQw1 were increased. The C4A gene deletion usually associated with SLE in Caucasoid and black patients was absent from all Chinese subjects, but possession of other C4 deletions and of DRw15 conferred the greatest risk (relative risk = 8.3). CONCLUSION: Different MHC haplotypes predispose to lupus in Chinese than in other ethnic groups. Our data suggest that the susceptibility lies at, or telomeric to, the DR locus, and that DRw15 and C4 deletions may act synergistically in conferring disease susceptibility.
Assuntos
Lúpus Eritematoso Sistêmico/genética , China/epidemiologia , Deleção Cromossômica , Complemento C4/genética , Suscetibilidade a Doenças , Frequência do Gene , Genes MHC Classe I , Genes MHC da Classe II , Antígenos HLA-DQ/genética , Antígenos HLA-DR/genética , Humanos , Alótipos de Imunoglobulina/genética , Nefrite Lúpica/genética , Complexo Principal de Histocompatibilidade/genética , Polimorfismo Genético , Polimorfismo de Fragmento de Restrição , Esteroide 21-Hidroxilase/genéticaRESUMO
Systemic lupus erythematosus (SLE) is highly prevalent in Malaysia, which has a mixed population of Malays, Chinese, and Indians. A quantitative enzyme linked immunosorbent assay (ELISA) was used to determine anticardiolipin antibody (aCL) levels (total immunoglobulin, IgG, and IgM) in 200 patients with SLE (164 Chinese, 26 Malay, and 10 Indian) attending the University Hospital of Kuala Lumpur, Malaysia, and 103 matched controls. Only 33 (16.5%) of the patients had raised aCL levels; 26 had raised IgG aCL, five IgM aCL, and two both IgG and IgM aCL. There was a low prevalence of raised levels of aCL in the population studied, which was seen in conjunction with a rare occurrence of thrombosis. The classical association of high aCL levels with thrombocytopenia and recurrent abortions was noted, though not with cerebral disease. The low prevalence of aCL in this study population of mixed racial origin contrasts with findings in European patients with SLE and lends support to the influence of local factors, be they genetic or environmental, on the clinical manifestations of this disease.
