Porphyrias
What is Porphyrias?
Porphyrias, Acute intermittent porphyria; Hereditary coproporphyria; Congenital erythropoietic porphyria; and Erythropoietic protoporphyria.
Blood - they are a group of disorders characterzed by photo-sensitivity , acute attacks of abdominal pain and neurologic abnormalities or both.
Porphyria Cutanea Tarda - disease with striking cutaneous manifestations.
Protoporphyria - inherited illness characterized by a unique type of photosensitivity.
Congenital Eyrthropoeitic Porphyria
Acute Intermittent Porphyria
Variegate Porphria and Hereditary Coproporphyria (VP and HCP)
Who gets Porphyrias?
Porphyria Cutanea Tarda - 1 in 25,000 caucasians, uncommon in African Americans.
Protoporphyria - this is relatively common but the exact incidence has not been determined. Hundreds of cases have been reported throughout the world.
Congenital Eyrthropoeitic Porphyria - Fewer than 300 cases have been rpeorted in the medical literature.
Acute Intermittent Porphyria - estimates of the defect have ranged from 1.5-10 per 100,000 but most carriers of a mutant allele never develop symptoms.
Variegate Porphria and Hereditary Coproporphyria - both are rare but VP occurs more often in South Africans of Dutch descent.
Predisposing Factors
Porphyria Cutanea Tarda - this is a disease of adults, mainly middle aged men who use alcohol regularly. Due to an enzymatic defect that is inherited in about half of cases.
Protoporphyria - inherited mutation in the gene for an enzyme which is involved in the synthesis of heme.
Congenital Eyrthropoeitic Porphyria - due to a severe deficiency of uroporphyrnogen III co-synthase.
Acute Intermittent Porphyria - mutations in the gene encoding porphobilinogen deaminase are responsible. The result is a partial block in the heme biosynthetic pathway. It is transmitted as an autosomal dominant trait.
Variegate Porphria and Hereditary Coproporphyria - both disorders are due to the autosomal dominant transmaission of mutant alleles resulting in enzymes that are deficient.
Progression
PCT: If liver iron stores are depleted and liver toxins avoided then it is likely that PCT will not affect life expectancy. There have been some reports in Europe of an increased risk of hepatocellular carcinoma but this has not been confirmed elsewhere.
Protoporphyria - This is a benign disease in most patients and progresses very little. The complication of cirrhosis with liver failure is rare and the only effective therapy for this complication is liver transplantation.
Congenital Eyrthropoeitic Porphyria - bone marrow transplantation is the only therapeutic option that reverses the disease pehnotype but the procedure is feasible only when normal HLA matched sibling donors are available. If phootmutilation can be avoided and if the haemolytic anaemia is not too severe, then affected individuals may lead long, productive lives.
Acute Intermittent Porphyria - If acute attacks are successfully prevented life expectancy is normal. Early effective treatment of the acute attcks that do occur usually prevents permanent nerve damage. The frequency of attacks in women usually declines after menopause.
Variegate Porphria and Hereditary Coproporphyria - the avoidance of offending drugs generally prevents the development of any attacks. If acute attacks are prevented, life expectancy is normal.
