C2 DEFICIENCY IN BLOOD-DONORS AND LUPUS PATIENTS - PREVALENCE, CLINICAL CHARACTERISTICS AND HLA-ASSOCIATIONS IN THE BRAZILIAN POPULATION

The objective of the present study was to investigate the prevalence, clinical characteristics, and HLA associations of C2 deficiency in the Brazilian population. The frequency of C2 deficiency profile (C2Q deg rees profile) was 2.2% among 1503 blood donors and 6.6% among 166 pati ents with systemic lupus erythematosus (SLE). A higher incidence of cl inical manifestations possibly related to immune complex disease was o bserved among blood donors with C2Q degrees profile and their relative s with C2Q degrees profile when compared to the normal C2 relatives. T he comparison of clinical and laboratory features between SLE patients with C2Q degrees profile and those with normal C2 revealed earlier di sease onset, higher frequency of oral ulcerations and lower frequency of anti-native DNA antibodies in the first group. The HLA study conduc ted on 18 individuals with C2Q degrees profile (11 blood donors and 7 SLE patients) confirmed the previously reported association with the a ntigens HLA-A25, B18 and DR2, supporting the concept that probably mos t C2 deficiency cases, throughout the world, are due to a single mutat ion in the C2 gene in linkage disequilibrium with the A25B18DR2 haplot ype.