The American journal of medicine
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Comparative Study
Relationship between C4 null genes, HLA-D region antigens, and genetic susceptibility to systemic lupus erythematosus in Caucasian and black Americans.
The complement components C4A, C4B, and factor B, and the HLA-A, B, C, DR, DQ, and DRw antigens were analyzed in 103 patients (66 Caucasian, 37 black) with systemic lupus erythematosus (SLE) and 98 control subjects (63 Caucasian, 35 black). Only the C4A null (silent) allele was significantly increased in SLE (0.254 versus 0.095 in Caucasians, p = 0.033; 0.200 versus 0.071 in blacks, p = 0.046). The absence of any detectable C4A gene products (homozygous C4A null or C4A*Q0,Q0) was found in 11.1 percent of Caucasian patients but in no control subjects (p = 0.006 with relative risk of 16.86). ⋯ Multivariate analysis demonstrated that the HLA-DR2 antigen and C4A null allele contributed independently to the risk of SLE (relative risk 3.0 and 3.2, respectively); when HLA-DR2 and the homozygous C4A null phenotype were present together, the relative risk of SLE was 24.9. Both HLA-B8 and HLA-DR3 were increased in SLE, but these antigens are in linkage disequilibrium with the C4A null allele; the presence of HLA-B8 or DR3 did not contribute further to the risk of SLE. It is concluded that the HLA-DR2 antigen and the C4A null allele are independent and additive risk factors for development of SLE.
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Case Reports
Angioneurotic edema, agranulocytosis, and fatal septicemia following captopril therapy.
Captopril, an angiotensin converting enzyme inhibitor used in the treatment of hypertension, has been associated with hematologic as well as dermatologic side effects. Two patients with captopril-induced angioneurotic edema, one of whom had fatal granulocytopenia and overwhelming polymicrobial sepsis, are presented.