Acquired

We use this term to describe how prominent the features of a porphyria are. If a porphyria is biochemically very active, then we expect to identify large amounts of porphyrin in sample such as urine and stool. If a porphyria is clinically very active, the patient should be experiencing obvious symptoms. The activity of a porphyria is related to its expression.

This is the commonest form of acute porphyria in most countries with the exception of South Africa. It results from a deficiency in the enzyme porphobilinogen deaminase (PBGD). It is inherited as an autosomal dominant condition. It manifests biochemically with elevated ALA and PBG levels which are commonly measured in the urine. Clinically it is associated with the acute attack, but patients with AIP do not develop photosensitivity.

The term used to describe those porphyrias which may be complicated by the acute attack: acute intermittent porphyria, hereditary coproporphyria, variegate porphyria and ALA dehydratase porphyria.

This is a very rare form of porphyria also known as Doss porphyria. It results from a deficiency in the enzyme ALA dehydratase (ALAD). It results in the accumulation of large amounts of ALA which may be measured in the urine and plasma. Patients may develop severe acute attacks but do not show photosensitivity. Typically the onset is as children or young adults. The disease is inherited as an autosomal recessive condition.

Drugs used for the prevention and treatment of seizures (fits). Many of the older anticonvulsants are particularly dangerous in porphyria.

An asymptomatic individual is one who shows no symptoms of their disease. See also symptomatic

Each individual inherits two copies of every gene: one from the mother and one from the father. In an autosomal dominant disorder, the individual will show signs of the disease even if only one copy of the gene is faulty, i.e. carries a mutation. Therefore only one parent need to be a carrier for the child to show signs of the disease. Most porphyrias are inherited as autosomal dominant disorders; acute intermittent porphyria, variegate porphyria, hereditary coproporphyria, erythropoietic protoporphyria and the hereditary form of porphyria cutanea tarda. See autosomal recessive, heterozygote, homozygote.

Each individual inherits two copies of every gene: one from the mother and one from the father. In an autosomal recessive disorder, the individual will show signs of the disease only if both copies of the gene are faulty, i.e. carry a mutation. Therefore both parents need to be carriers for the child to show signs of the disease. The only porphyrias which are inherited as autosomal recessive conditions are ALA dehydratase deficiency porphyria and congenital erythropoietic porphyria (CEP). See autosomal dominant, heterozygote, homozygote.

These are tests based on the identification and measuring of porphyrins in samples such as blood, urine and stool. ALA, PBG and porphyrins are usually measured by chromatography. A common biochemical test is the plasma scan which recognizes abnormal accumulations of porphyrins in the plasma by fluorescence. The other type of test commonly used for the diagnosis of porphyria is a DNA test (or genetic) test.

An individual who carries a mutation in the gene and may pass it on to his or her children.

This is a biochemical laboratory technique in which the individual porphyrins are separated out from a sample such as urine, blood or stool. Each type of porphyrin can then be measured separately. This allows the specialist to identify not only by how much porphyrins are increased, but also the pattern of accumulation, which is very helpful in making a diagnosis. Techniques in use are thin layer chromatography, where the porphyrins are separated out on the surface of a specially treated plate, and high-performance liquid chromatography, in which the porphyrins are separated as they pass through a column of special material.

Medications which consist of more than one active ingredient. Examples include many common over-the-counter remedies for colds and flu, and the combined oral contraceptive pill. Compound medications are particularly troublesome in patients with porphyria, since at least one of the ingredients may be dangerous, and there is even the possibility that the combination of ingredients will be more likely to induce haem synthesis than any one component on its own.

The seventh chemical substance and the fifth porphyrin on the haem synthetic pathway. A tetrapyrrole containing four carboxylic side chains. Coproporphyrin is excreted in both urine and stool, and is commonly measured by porphyrin laboratories in urine, stool, red blood cells and plasma.

A laboratory test in which a patient's DNA is tested for the presence of mutations. The test is usually very specific for both a particular form of porphyria and even for a particular family.

Every individual carries two copies of every gene. Individuals carrying two abnormal copies of the gene, each containing the identical mutation, associated with a disease are said to be homozygous, and are known as homozygotes. Individuals who carry two faulty copies of the gene, but who have a different mutation in each, are said to be heterozygous and are known as double heterozygotes.

The conversion of a drug within the body from the original chemical compound into other compounds. Most drugs taken systemically are metabolized; in some cases the metabolism is necessary for the drug to become active, in other cases, the metabolism is necessary for the drug to be deactivated and excreted. The liver is very active in drug metabolism; a class of enzyme known as the cytochrome P450s are involved. The cytochromes contain haem, formed by the haem synthetic pathway. When the cytochromes are induced as a result of drug administration, haem synthesis is increased. This is an important mechanism whereby drug administration in a person with porphyria may result in an acute attack.

People who have inherited a mutation capable of giving rise to porphyria vary in the extent to which they show the disease: some may be severely affected, some moderately affected whereas others may show no sign of the disease at all. The extent to which the disease shows itself is referred to as the expression of the disease (or of the mutation). Thus a person may express porphyria severely, to a moderate extent or not all.

A test result suggesting that an individual does not have porphyria when in fact they do. This is commonly encountered in patients who do not express porphyria, even though they have inherited a mutation.

A test result suggesting an individual has porphyria when in fact they do not.

This is the official chemical name of a drug. There is only one generic name for each drug. Many companies may make the same drug, and each will provide its own trade name for the drug. In view of the multiplicity of trade names, and the fact that they are continually changing, drug lists are built around lists of generic names. It is therefore important to to find out the correct generic name for your drug before searching our lists, as you will not find the trade name listed here.

The production of haem by the haem synthetic pathway.

The fourth chemical substance and the second porphyrin on the haem synthetic pathway. A tetrapyrrole containing seven carboxylic side chains. Only trace amounts are present in urine in normal people, but heptacarboxylic porphyrin may accumulate in some forms of porphyria, particularly PCT.

Every individual carries two copies of every gene. Individuals carrying one normal copy and one abnormal copy of the gene associated with a disease are said to be heterozygous, and are known as heterozygotes. If a porphyria is inherited as an autosomal dominant condition, then heterozygotes may show the disease since only one faulty copy is necessary for the disease to manifest.

Every individual carries two copies of every gene. Individuals in whom both copies of a gene are defective are said to be homozygous, and are known as homozygotes. If a porphyria is inherited as an autosomal recessive condition, then only homozygotes will show the disease since two faulty copies are necessary for the disease to manifest. Strictly speaking, each faulty gene must carry an identical mutation for an individual to be a homozygote. Individuals who carry two faulty copies of the gene, but who have a different mutation in each, are known as double heterozygotes.

This refers to the process whereby the synthesis (or production) of chemical compounds is increased (i.e. induced) in the body in response to appropriate triggering factors. Two forms of induction are important in porphyria. Haem synthesis is induced in response to an increased need for haem, which may aggravate the porphyria. Secondly, a group of enzymes called the cytochrome P450 enzymes are induced in response to the administration of many drugs. Since the cytochrome P450s require haem, administration of those drugs results in increased haem synthesis which may aggravate porphyria and even result in an acute attack.

The sixth chemical substance and the fourth porphyrin on the haem synthetic pathway. A tetrapyrrole containing five carboxylic acid side chains. Pentacarboxylic porphyrin is found in small amounts in urine and plasma. Increased amounts are found in both porphyria cutanea tarda (PCT) and variegate porphyria (VP).

A disorder of haem synthesis accompanied by an abnormal accumulation of porphyrins, which may be measured in the urine, plasma and blood.

The porphyrin precursors are aminolaevulinic acid (ALA) and porphobilinogen (PBG). These are the first two intermediate substances on the haem synthetic pathway. They are known as precursors as chemically they have not yet attained the tetrapyrrole configuration typical of the porphyrins. The precursors are particularly elevated in patients with acute intermittent porphyria and in patients with variegate porphyria and hereditary coproporphyria experiencing the acute attack. The porphyrin precursors are excreted in urine and are therefore measured in urine samples.

A technical term describing how, and how uncommon a particular disease is in a population. South Africa has a high prevalence of variegate porphyria, meaning that the condition is common.

The eighth and final chemical substance on the haem synthetic pathway before haem itself. A tetrapyrrole containing two carboxylic side chains. Protoporphyrin is excreted in the stool, and is commonly measured by porphyrin laboratories in stool and red blood cells.

This is shorthand for the very common mutation in the gene for protoporphyrinogen oxidase causing variegate porphyria in most South African patients. The abbreviation indicates that arginine (R) is replaced by tryptophan (W) at the 59th amino acid of the enzyme protoporphyrinogen oxidase.

An individual who is symptomatic is one who is experiencing symptoms of their disease.

A chemical substance consisting of four pyrrole rings, joined together into a single large ring known as a macrocycle. All the porphyrins are tetrapyrroles.

Topical preparations are those which are applied directly to the skin or mucous membranes. Examples include ointments, creams and lotions. This is in contrast to systemic preparations, which may be taken orally or by injection, and work through the system rather than directly on the body's surface.

Every drug has only one official technical name: its generic name. Many companies may make the same drug, and each will provide its own name for its product; this is known as its trade name. In view of the multiplicity of trade names, and the fact that they are continually changing, drug lists are built around lists of generic names. It is therefore important to to find out the correct generic name for your drug before searching our lists, as you will not find the trade name listed here.

The third chemical substance and the first porphyrin on the haem synthetic pathway. A tetrapyrrole containing eight carboxylic side chains. Large amounts of uroporphyrin are excreted in the urine in normal subjects, and these amounts are increased in some forms of porphyria.

A simple biochemical test in which urine is treated with a reagent called Ehrlich's aldehyde. This test can detect increased levels of porphobilinogen, which may help to confirm a clinical diagnosis of the acute attack in a patient with an acute porphyria.