Variegate porphyria

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Variegate porphyria
Other namesMixed hepatic porphyria,[1] Mixed porphyria,[1] South African genetic porphyria,[1]: 525  and South African porphyria.[2]
Protoporphyrinogen IX
SpecialtyEndocrinology Edit this on Wikidata
Symptomsskin problems, Enzyme difficiency.
Causesgenetic mutations.
Treatmentliver transplants.

Variegate porphyria, also known by

organs. It is a component of hemoglobin, the molecule that carries oxygen in the blood
.

Signs and symptoms

When symptoms occur, they can include acute attacks (similar to

diarrhoea and constipation. During an attack, a person may also experience muscle weakness, seizures, and mental changes such as anxiety and hallucinations. These signs and symptoms are triggered by nongenetic factors such as certain drugs, dieting or fasting, certain hormones and stress.[citation needed
]

Some people with variegate porphyria have skin that is overly sensitive to

pigmentation, and increased hair growth. Exposed skin becomes fragile and is easily damaged.[citation needed
]

Rarely, the signs and symptoms of variegate porphyria can begin in infancy or early childhood. In such cases, the signs and symptoms are usually more severe than those starting later in life.[citation needed]

Genetics

Variegate porphyria has an autosomal dominant pattern of inheritance.

mitochondrial enzyme called protoporphyrinogen oxidase, which is critical to the chemical process that leads to heme production. The activity of this enzyme is reduced by 50 percent in most people with variegate porphyria. In severe cases that begin early in life, the enzyme is almost completely inactive. Nongenetic factors such as certain drugs, stress, and others listed above can increase the demand for heme and the enzymes required to make heme. The combination of this increased demand and reduced activity of protoporphyrinogen oxidase disrupts heme production and allows byproducts of the process to accumulate in the liver, triggering an acute attack.[citation needed
]

Variegate porphyria is inherited in an

autosomal dominant pattern, which means the defective gene is located on an autosome, and inheriting one copy of the defective gene from an affected parent is sufficient to cause the disorder. More severe cases result from inheriting two copies of the defective gene.[citation needed
]

The entire PPOX gene has about 8kb with 13 exon sequences. It was successfully cloned from a cDNA library in 1995 revealing that, after processing, it is 477 nucleotides long. It has previously been thought that the PPOX gene was located on human chromosome 14,[5] however mapping experiments (FISH) have shown that it is near 1q23.[6] An additional aggravating mutation affecting variegate porphyria can be found at 6p21.3 on the HFE gene.[7]

A 2006 clinical, biochemical and mutational study of eight Swiss variegate porphyria patients and their families found four novel PPOX gene mutations believed to be unique to the Swiss population.[8]

Diagnosis

Diagnosis is by finding raised urine porphyrins, raised faecal porphyrins, markedly raised plasma porphyrins (pathognomic) and finding photosensitive cutaneous lesions on clinical examination.[citation needed]

Treatment

Liver transplant has been used in the treatment of this condition.[9]

Epidemiology

In South Africa, the prevalence of variegate porphyria is approximately 1 in 300.[10] In Finland, the prevalence is approximately 1 in 75,000.[11]

It is also found in Argentina,[12] Sweden,[13] and Australia.[14]

References

  1. ^
    ISBN 978-0-7216-2921-6
    .
  2. ISBN 978-1-4160-2999-1
    .
  3. ^ "porphyria variegata" at Dorland's Medical Dictionary
  4. S2CID 40665725
    .
  5. S2CID 27271722
    .
  6. PMID 8634714
    .
  7. PMID 10401000
    .
  8. S2CID 33670384
    .
  9. PMID 15237381
    .
  10. ISBN 978-1-4051-3400-2
    .
  11. PMID 7433635
    .
  12. PMID 18570668
    .
  13. S2CID 38314848
    .
  14. S2CID 34572600.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )

This article incorporates public domain text from The U.S. National Library of Medicine

External links

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