hepatic porphyria


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porphyria

 [por-fēr´e-ah]
a genetic disorder characterized by a disturbance in porphyrin metabolism with resultant increase in the formation and excretion of porphyrins (uroporphyrin and coproporphyrin) or their precursors; called also hematoporphyria. Porphyrins, in combination with iron, form hemes, which in turn combine with specific proteins to form hemoproteins. hemoglobin is a hemoprotein, as are many other substances essential to normal functioning of the cells and tissues of the body.

Two general types are known: the erythropoietic porphyrias, which are concerned with the formation of erythrocytes in the bone marrow; and the hepatic porphyrias, which are responsible for liver dysfunction. Manifestations of porphyria include gastrointestinal, neurologic, and psychologic symptoms, cutaneous photosensitivity, pigmentation of the face (and later of the bones), and anemia with enlargement of the spleen. Large amounts of porphyrins are excreted in the urine and feces.

Treatment of this condition has been primarily symptomatic and varies in its effectiveness. Emphasis is on prevention of attacks by avoiding fasting and drugs that precipitate the symptoms. Photosensitivity may be controlled by avoiding exposure to light. Removal of the spleen is useful in some cases of the erythropoietic type of porphyria. Drug therapy includes the use of phenothiazines, chlorpromazine and promazine in particular. These drugs allay pain and nervousness and apparently allow a period of remission from symptoms. Meperidine hydrochloride (Demerol) may be given for pain and hydroxypheme (Hemetin) is given intravenously to compensate for genetic impairment of heme synthesis.

Patients with porphyria must not be given barbiturates, sulfonamides, alcohol, or chloroquine as these chemicals may precipitate or intensify attacks. It is recommended that persons with this disease carry with them at all times identification saying that they have porphyria so that in an emergency they will not be given medication that could precipitate an attack or even death.
acute intermittent porphyria (AIP) a hereditary, autosomal dominant, form of hepatic porphyria manifested by recurrent attacks of abdominal pain, gastrointestinal dysfunction, and neurologic disturbances, and by excessive amounts of δ-aminolevulinic acid and porphobilinogen in the urine; it is due to an abnormality of pyrrole metabolism. Called also intermittent acute porphyria.
congenital erythropoietic porphyria (CEP) a form of erythropoietic porphyria, with cutaneous photosensitivity leading to mutilating lesions, hemolytic anemia, splenomegaly, excessive urinary excretion of uroporphyrin and coproporphyrin, and invariably erythrodontia and hypertrichosis. Called also Günther disease.
porphyria cuta´nea tar´da (PCT) the most common form of porphyria, characterized by cutaneous photosensitivity that causes scarring bullae, discoloration, growth of facial hair, and sometimes sclerodermatous thickenings and alopecia; it is frequently associated with alcohol abuse, liver disease, or hepatic siderosis. Urinary levels of uroporphyrin and coproporphyrin are increased. There are two main types: an autosomal dominant (or familial ) form in which activity of the affected enzyme is reduced to half normal in liver, erythrocytes, and fibroblasts; and a sporadic (but probably also familial) form in which the reduction is confined to the liver. Both types are believed to be heterozygous and clinical expression occurs in adulthood, precipitated by disease or environmental factors. A more severe homozygous form begins in childhood and is called hepatoerythropoietic porphyria.
erythropoietic porphyria porphyria in which excessive formation of porphyrin or its precursors occurs in bone marrow erythroblasts; the group includes congenital erythropoietic porphyria and erythropoietic protoporphyria.
hepatic porphyria porphyria in which the excess formation of porphyrin or its precursors is found in the liver; it includes acute intermittent porphyria, variegate porphyria, and hereditary coproporphyria.
hepatoerythropoietic porphyria (HEP) a severe homozygous form of porphyria cutanea tarda believed to result from an autosomal dominant defect in the same enzyme as is affected in porphyria cutanea tarda; it is clinically identical to that disease but onset is in early childhood and enzyme activity in liver, erythrocytes, and fibroblasts is virtually absent.
intermittent acute porphyria acute intermittent porphyria.
porphyria variega´ta (variegate porphyria (VP)) a hereditary, autosomal dominant, type of hepatic porphyria characterized by chronic cutaneous manifestations, notably extreme mechanical fragility of the skin, particularly areas exposed to the sunlight, and by episodes of abdominal pain and neuropathy. There is typically an excess of coproporphyrin and protoporphyrin in the bile and feces.

he·pa·tic por·phyr·i·a

[MIM*176100.0002]
a category of porphyria that includes porphyria cutanea tarda, variegate porphyria, and coproporphyria.
Synonym(s): porphyria hepatica

hepatic porphyria

Metabolic disorders A general term which encompasses acute hepatic porphyrias, porphyria cutanea tarda and hepatoerythropoietic porphyria. See Porphyria.

he·pat·ic por·phyr·i·a

(hĕ-pat'ik pōr-fir'ē-ă)
A category of porphyria that includes porphyria cutanea tarda, variegate porphyria, and coproporphyria.
References in periodicals archive ?
Overall Health, Daily Functioning, and Quality of Life in Acute Hepatic Porphyria Patients: ENVISION, a Phase 3 Global, Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial
The acute hepatic porphyrias are autosomal dominant conditions with low penetrance and include acute intermittent porphyria, hereditary coproporphyria and variegate porphyria.
Stimulation of liver home oxygenase in hexachlorobenzene-induced hepatic porphyria. Arch Toxicol 72:355-361.
- The US Food and Drug Administration has accepted US-based RNAi therapeutics company Alnylam Pharmaceuticals, Inc.'s (NASDAQ: ALNY) New Drug Application for givosiran, an investigational RNAi therapeutic targeting aminolevulinic acid synthase 1 (ALAS1) in development for the treatment of acute hepatic porphyria, and granted Priority Review for the NDA, the company said.
Food and Drug Administration (FDA) has accepted the Company's New Drug Application (NDA) for givosiran, an investigational RNAi therapeutic targeting aminolevulinic acid synthase 1 (ALAS1) in development for the treatment of acute hepatic porphyria (AHP), and granted Priority Review for the NDA.
(NASDAQ: ALNY) has submitted a Marketing Authorization Application to the European Medicines Agency for givosiran, an investigational RNAi therapeutic targeting aminolevulinic acid synthase 1 (ALAS1) in development for the treatment of acute hepatic porphyria, the company said.
(NASDAQ: ALNY) has completed a rolling submission of a New Drug Application to the US Food and Drug Administration for givosiran, an investigational RNAi therapeutic targeting aminolevulinic acid synthase 1 (ALAS1) in development for the treatment of acute hepatic porphyria, the company said.
Hereditary hepatic porphyria due to homozygous [delta]-aminolevulinic acid dehydratase deficiency: studies in lymphocytes and erythrocytes.
- US-based RNAi therapeutics company Alnylam Pharmaceuticals, Inc.'s (NASDAQ: ALNY) ENVISION Phase 3 study of givosiran, an investigational RNAi therapeutic targeting aminolevulinic acid synthase 1 (ALAS1) in development for the treatment of acute hepatic porphyria, met its primary efficacy endpoint and the majority of secondary endpoints, the company said.
Alnylam Pharmaceuticals announced that the Company presented updated results from the ongoing Phase 1/2 open-label extension study of givosiran, an investigational RNAi therapeutic, targeting aminolevulinic acid synthase 1 for the treatment of acute hepatic porphyria. As of the data cut-off date of June 7, 2018, a robust treatment effect was maintained in givosiran-treated patients with continued dosing in the Phase 1/2 OLE study, with a mean time on treatment of 13.6 months and total time on treatment across the Phase 1 and OLE studies of up to 25 months.
- Results from the Phase 1 study of US-based RNAi therapeutics company Alnylam Pharmaceuticals, Inc.'s (NASDAQ: ALNY) givosiran, an investigational, subcutaneous RNAi therapeutic targeting aminolevulinic acid synthase 1 (ALAS1) for the treatment of acute hepatic porphyria, were published online this week The New England Journal of Medicine (NEJM), the company said.
Food and Drug Administration, the Company plans to pursue a full approval based on the complete results of the ENVISION Phase 3 study of givosiran, an investigational RNAi therapeutic targeting aminolevulinic acid synthase 1 for the treatment of acute hepatic porphyria, rather than filing based on the interim Phase 3 results.