Thursday, October 3, 2013

Porphyria and background resources


Background

Porphyria is named from the ancient Greek word porphura, meaning purple.[1] Porphyrins are precursors of heme, a part of the hemoglobin molecule. Heme is manufactured in a multistep process. Defects of enzymes needed at various steps of heme synthesis result in distinct clinical syndromes known as porphyrias. These syndromes can be clinically classified into those predominantly involving the skin, those manifesting as disorders of the liver/nervous system, and a combination involving all 3 entities (see the image below).
Clinical classification of porphyrias. Clinical classification of porphyrias. Porphyrias can be inherited or (rarely) acquired.[2] With the exception of congenital erythropoietic porphyria (CEP), which is autosomal recessive, all other porphyrias are inherited as autosomal dominant disorders. They invariably result in accumulation and increased excretion of porphyrins and their precursors. Some porphyrias have acute presentations (acute intermittent, variegate, hereditary coproporphyria), whereas others have a chronic, relatively stable presentation (congenital, erythropoietic).[3]
King George III of England had symptoms of abdominal pain, rashes, reddish urine, and psychotic episodes that are consistent with porphyria, although the account is disputed by many.[4] During the period 1955-1959, approximately 4000 people in southeast Anatolia (Turkey) developed porphyria due to the ingestion of hexachlorobenzene (HCB), a fungicide that was added to wheat seedlings.[5]

References
  1. Lane N. Born to the purple: the story of porphyria. Scientific American [serial online]. December 16, 2002;Accessed September 30, 2009. Available at http://www.scientificamerican.com/article.cfm?id=born-to-the-purple-the-st.
  2. Champe PC, Harvey RA, eds. Conversion of amino acids to specialized products. Biochemistry. 2nd ed. Philadelphia, Pa: Lippincott, Williams & Wilkins; 1994:260-1.
  3. Forbes CD, Jackson WF, eds. Endocrine, metabolic and nutritional. Color Atlas and Text of Clinical Medicine. 2nd ed. Barcelona, Spain: Times Mirror International / Mosby; 1997:349.
  4. Cooper J. King George's illness -- porphyria. Queen Charlotte, 1744-1818: A Bilingual Exhibit. Available at http://people.virginia.edu/~jlc5f/charlotte/porphyria.html. Accessed February 4, 2008.
  5. Gocmen A, Peters HA, Cripps DJ, Bryan GT, Morris CR. Hexachlorobenzene episode in Turkey. Biomed Environ Sci. Mar 1989;2(1):36-43. [Medline].
  6. Poblete-Gutierrez P, Badeloe S, Wiederholt T, Merk HF, Frank J. Dual porphyrias revisited. Exp Dermatol. Sep 2006;15(9):685-91. [Medline]. [Full Text].
  7. Canavese C, Gabrielli D, Guida C, Cappellini MD. [Nephrologists and porphyrias] [Italian]. G Ital Nefrol. Jul-Aug 2002;19(4):393-412. [Medline].
  8. Doss MO, Stauch T, Gross U, et al. The third case of Doss porphyria (delta-amino-levulinic acid dehydratase deficiency) in Germany. J Inherit Metab Dis. 2004;27(4):529-36. [Medline].
  9. Hedger RW, Wehrmacher WH, French AV. Porphyria syndrome associated with diabetic nephrosclerosis and erythropoietin. Compr Ther. 2006;32(3):163-71. [Medline].

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