Starting from the known association between psoriasis and several HLA antigens and from the fact that the HLA chromosomal region contains the structural genes for at least three complement components, the authors have looked for an association between psoriasis and allotypes of C2 and BF. C2 and BF polymorphism were examined in 230 psoriatic patients. Two rare complement genes were found to be significantly increased when compared with controls: the frequency of the C2*2 gene was 0.061 among patients and 0.035 among controls (P less than 0.05); for BF*SO7, the frequencies were 0.0304 in patients and 0.0092 in controls (P less than 0.0005). The BF*F gene frequency, however, was significantly decreased among patients: 0.1196 vs. 0.1743 (P less than 0.01). The relative risks were 1.79 for the C2 2, 3.44 for the BF SO7, and 0.6 for the BF F gene product. From previous studies, it is known that these three complement alleles (C2*2, BF*SO7, BF*F) are in linkage disequilibrium with HLA alleles that have also been found increased or decreased, respectively, in psoriasis.
A chronic hepatic disorder of porphyrin metabolism was found in 36 workers with vinyl chloride (VC)-induced hepatic injury following long-time industrial exposure. Pathologic porphyrinuria, especially secondary coproporphyrinuria with transition to subclinical chronic hepatic porphyria, is a consistent pathobiochemical parameter for the recognition of VC hepatic lesions. The porphyrinuria is of diagnostic value for the incipient toxic phase. Erythrocyte uroporphyrinogen decarboxylase activity studied in six cases with initial chronic hepatic porphyria was normal, suggesting that VC affects only this enzyme in the liver.
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