Book contents
- Frontmatter
- Contents
- Foreword by Anthony S. Tavill
- Preface
- 1 History of iron overload disorders
- 2 Normal iron absorption and metabolism
- 3 Iron toxicity
- 4 Tests for hemochromatosis and iron overload
- 5 Complications of hemochromatosis and iron overload
- 6 Insulin resistance and iron overload
- 7 Infections and immunity
- 8 Classical and atypical HFE hemochromatosis
- 9 Heterozygosity for HFE C282Y
- 10 Porphyria cutanea tarda
- 11 Mitochondrial mutations as modifiers of hemochromatosis
- 12 Hemochromatosis associated with ferroportin gene (SLC40A1) mutations
- 13 Hemochromatosis associated with hemojuvelin gene (HJV) mutations
- 14 Hemochromatosis associated with hepcidin gene (HAMP) mutations
- 15 Hemochromatosis associated with transferrin receptor-2 gene (TFR2) mutations
- 16 Iron overload associated with IRE mutation of ferritin heavy-chain gene (FTH1)
- 17 Hereditary hyperferritinemia-cataract syndrome: IRE mutations of ferritin light-chain gene (FTL)
- 18 Iron overload in Native Africans and African-Americans
- 19 Hereditary atransferrinemia
- 20 Divalent metal transporter-1 (SLC11A2) iron overload
- 21 Iron overload associated with thalassemia syndromes
- 22 Iron overload associated with hemoglobinopathies
- 23 Iron overload associated with pyruvate kinase deficiency
- 24 Iron overload associated with congenital dyserythropoietic anemias
- 25 Hereditary sideroblastic anemias
- 26 Pearson marrow–pancreas syndrome
- 27 Acquired sideroblastic anemias
- 28 Hereditary aceruloplasminemia
- 29 Friedreich ataxia and cardiomyopathy
- 30 Pantothenate kinase (PANK2)-associated neurodegeneration
- 31 Neuroferritinopathies
- 32 GRACILE syndrome
- 33 Neonatal hemochromatosis
- 34 Iron overload due to excessive supplementation
- 35 Localized iron overload
- 36 Management of iron overload
- 37 Population screening for hemochromatosis
- 38 Ethical, legal, and social implications
- 39 Directions for future research
- Index
- Plate section
- References
10 - Porphyria cutanea tarda
Published online by Cambridge University Press: 01 June 2011
- Frontmatter
- Contents
- Foreword by Anthony S. Tavill
- Preface
- 1 History of iron overload disorders
- 2 Normal iron absorption and metabolism
- 3 Iron toxicity
- 4 Tests for hemochromatosis and iron overload
- 5 Complications of hemochromatosis and iron overload
- 6 Insulin resistance and iron overload
- 7 Infections and immunity
- 8 Classical and atypical HFE hemochromatosis
- 9 Heterozygosity for HFE C282Y
- 10 Porphyria cutanea tarda
- 11 Mitochondrial mutations as modifiers of hemochromatosis
- 12 Hemochromatosis associated with ferroportin gene (SLC40A1) mutations
- 13 Hemochromatosis associated with hemojuvelin gene (HJV) mutations
- 14 Hemochromatosis associated with hepcidin gene (HAMP) mutations
- 15 Hemochromatosis associated with transferrin receptor-2 gene (TFR2) mutations
- 16 Iron overload associated with IRE mutation of ferritin heavy-chain gene (FTH1)
- 17 Hereditary hyperferritinemia-cataract syndrome: IRE mutations of ferritin light-chain gene (FTL)
- 18 Iron overload in Native Africans and African-Americans
- 19 Hereditary atransferrinemia
- 20 Divalent metal transporter-1 (SLC11A2) iron overload
- 21 Iron overload associated with thalassemia syndromes
- 22 Iron overload associated with hemoglobinopathies
- 23 Iron overload associated with pyruvate kinase deficiency
- 24 Iron overload associated with congenital dyserythropoietic anemias
- 25 Hereditary sideroblastic anemias
- 26 Pearson marrow–pancreas syndrome
- 27 Acquired sideroblastic anemias
- 28 Hereditary aceruloplasminemia
- 29 Friedreich ataxia and cardiomyopathy
- 30 Pantothenate kinase (PANK2)-associated neurodegeneration
- 31 Neuroferritinopathies
- 32 GRACILE syndrome
- 33 Neonatal hemochromatosis
- 34 Iron overload due to excessive supplementation
- 35 Localized iron overload
- 36 Management of iron overload
- 37 Population screening for hemochromatosis
- 38 Ethical, legal, and social implications
- 39 Directions for future research
- Index
- Plate section
- References
Summary
Porphyrias are disorders caused by heritable or acquired deficiency of an enzyme that is required for the normal synthesis of heme. A ring structure, heme is formed by the insertion of an iron atom into protoporphyrin in the final step of the porphyrin synthesis pathway. The usual presenting symptoms and signs of porphyrias are either skin photosensitivity or neurovisceral symptoms and signs. Three types of porphyria are characterized by a predominance of photosensitivity (porphyria cutanea tarda (PCT), congenital erythropoietic porphyria, and erythropoietic protoporphyria). Two types of porphyria are characterized mainly by neurovisceral symptoms and signs (acute intermittent porphyria and aminolevulinate dehydratase deficiency). The two remaining types of porphyria are characterized by both photosensitivity and neurovisceral symptoms and signs (hereditary coproporphyria and variegate porphyria). The seven main types of porphyria, the associated enzyme deficiency, the mode of inheritance, and the major presenting symptoms and signs are displayed in Table 10.1. The only type of porphyria discussed here is PCT, the most common of all porphyrias.
Porphyria cutanea tarda (PCT)
PCT is estimated to occur in about 1 per 5000 to 25,000 individuals in the general population. PCT is caused by decreased specific activity of the uroporphyrinogen decarboxylase enzyme, the fifth enzyme in the heme synthesis pathway. Three types of PCT can be identified on the basis of decreased activity of the uroporphyrinogen decarboxylase enzyme (URO-D) in liver cells or in erythrocytes.
- Type
- Chapter
- Information
- Handbook of Iron Overload Disorders , pp. 160 - 168Publisher: Cambridge University PressPrint publication year: 2010