[Significance and prevalence of the C282Y gene mutation of primary hemochromatosis in the pathogenesis of pophyria cutanea tarda].

BACKGROUND

Hitherto studies on the ethiopathogenesis of porphyria cutanea tarda (PCT) show that the major pathogenic factor is iron ion, which acts via inhibition of the uroporphyrinogen decarboxylase. New speculations have appeared on the possible relation of this role of iron and the occurrence of mutation of the recently discovered gene of the hereditary hemochromatosis HFE, which may cause the iron overloading of the organism. Our paper describes prevalence of the C282Y gene mutation (HFE) together with the clinical and laboratory record in PCT patients.

METHODS AND RESULTS

PCT was diagnosed mostly on the basis of clinical finding of actinic-traumatic vesicular dermatitis and the typical laboratory record of elevated higher-carboxylic porphyrines in urine and stool. Other laboratory methods tested the liver functions, plasma iron level and its binding capacity, ferritine level. All patient underwent routine haematological testing. Presence of antibodies against hepatitis C was also assayed (Elisa test 2nd generation, Sanofi Pasteur). In patients with prominent laboratory alterations showing possibility of the hepatic structural lesion, histology from the liver punctate was done. Frequency data of the C282Y gene mutation (HFE) in PCT patients was estimated on the basis of the genetic testing using PCR reaction of our own system. Group of PCT patients had 69 persons (63 patients with the sporadic form and 6 patients with familiar form of the disease). Hereditary haemochromatosis C282Y gene mutation (HH) was found in 15 patients, three of them were homozygotes and twelve heterozygotes (three heterozygotes had the familiar form of the disease). Nobody in this group was positive in the HIV antibody testing. In all porphyria patients with the presence of mutated gene who underwent liver biopsy, siderosis of different degrees was identified. In three patients neither the phenotypic observation nor the laboratory testing have shown haemochromatosis. Prevalence of C282Y gene mutation HFE in patients with porphyria cutanea tarda was studied. Such mutation was found in 15 persons (12 heterozygotes and 3 homozygotes) from the group of 69 tested patients (21.7%). Such frequency is significantly higher than in the control--nonporphyric--persons (10%). Patients were without clinical symptoms. Laboratory haematological changes, typical for HH, manifested in some of them only (elevated level of ferritine was found in 10 from 15 porphyria patients, elevated sideremia in one of them). Red blood cell counts were in both homo- and heterozygotes normal. Concurrence of the two porphyrinogenic factors--presence of gene mutation HFE and hepatitis C infection--was not proved. Antibodies against hepatitis C virus were not identified in any of the patients. Siderosis was found to be only a symptomatic sign, which was pronounced in different degree in all 9 porphyria patients with C282Y gene mutation who underwent liver biopsy.

CONCLUSIONS

Frequency of C282Y gene mutation in our patients with porphyria cutanea tarda appears similar to that in other Middle European countries. It differs significantly from the frequency found in South European and North European countries (British).