Different patterns of human porphyria

From chemistry to genomics: A concise history of the porphyrias

We describe developments in understanding of the porphyrias associated with each step in the haem biosynthesis pathway and the role of individuals whose contributions led to major advances over the past 150 years. The first case of erythropoietic porphyria was reported in 1870, and the first with acute porphyria in 1889. Photosensitisation by porphyrin was confirmed by Meyer-Betz, who self-injected haematoporphyrin. Günther classified porphyrias into haematoporphyria acuta, acuta toxica, congenita and chronica. This was revised by Waldenström into porphyria congenita, acuta and cutanea tarda, with the latter describing those with late-onset skin lesions. Waldenström was the first to recognise porphobilinogen's association with acute porphyria, although its structure was not solved until 1953. Hans Fischer was awarded the Nobel prize in 1930 for solving the structure of porphyrins and the synthesis of haemin. After 1945, research by several groups elucidated the pathway of haem biosynthesis and its negative feedback regulation by haem. By 1961, following the work of Watson, Schmid, Rimington, Goldberg, Dean, Magnus and others, aided by the availability of modern techniques of porphyrin separation, six of the porphyrias were identified and classified as erythropoietic or hepatic. The seventh, 5-aminolaevulinate dehydratase deficiency porphyria, was described by Doss in 1979. The discovery of increased hepatic 5-aminolaevulinate synthase activity in acute porphyria led to development of haematin as a treatment for acute attacks. By 2000, all the haem biosynthesis genes were cloned, sequenced and assigned to chromosomes and disease-specific mutations identified in all inherited porphyrias. These advances have allowed definitive family studies and development of new treatments.

A challenging diagnosis for potential fatal diseases: recommendations for diagnosing acute porphyrias

Acute porphyrias are a heterogeneous group of metabolic disorders resulting from a variable catalytic defect of four enzymes out of the eight involved in the haem biosynthesis pathway; they are rare and mostly inherited diseases, but in some circumstances, the metabolic disturbance may be acquired. Many different environmental factors or pathological conditions (such as drugs, calorie restriction, hormones, infections, or alcohol abuse) often play a key role in triggering the clinical exacerbation (acute porphyric attack) of these diseases that may often mimic many other more common acute medical and neuropsychiatric conditions and whose delayed diagnosis and treatment may be fatal. In order to obtain an accurate diagnosis of acute porphyria, the knowledge and the use of appropriate diagnostic tools are mandatory, even in order to provide as soon as possible the more effective treatment and to prevent the use of potentially unsafe drugs, which can severely precipitate these diseases, especially in the presence of life-threatening symptoms. In this paper, we provide some recommendations for the diagnostic steps of acute porphyrias by reviewing literature and referring to clinical experience of the board members of the Gruppo Italiano Porfiria (GrIP).

Hereditary hepatic porphyrias in Finland

The occurrence of hepatic porphyrias--acute intermittent porphyria (AIP) and variegate porphyria (VP)--in Finland has been studied. During a period of 9 years 107 patients with AIP and 45 patients with VP were found. The prevalence of hereditary hepatic porphyrias was calculated to be 3.4 per 100 000 inhabitants. The patients belonged to 42 different families. Eighty-nine patients (59%) had had acute attacks, whereas 63 were symptomless latent cases. Precipitating factors, symptoms and excretion of porphyrins and their precursors did not significantly differ from what has been reported earlier from other parts of the world. A slight fragility of the skin on the back of the hands was noted in some 50% of VP patients. Abnormal sensitivity to sunlight could not be seen in a single case. However, about 50% of patients with VP showed an abnormal reaction when irradiated with artificial ultraviolet light. The difference in the skin symptoms in South African and Finnish VP patients is discussed.

Heterogeneity of familial porphyria cutanea tarda

The concentration of immunoreactive uroporphyrinogen decarboxylase has been measured in erythrocytes from 17 patients with porphyria cutanea tarda (PCT) from 10 families, from 74 of their relatives, and from 47 control subjects. The 10 families were divided into two groups according to their erythrocyte enzyme concentrations. Group A contained four families in which at least two subjects had overt PCT. All members of these families, including seven patients with overt PCT, had normal erythrocyte uroporphyrinogen decarboxylase concentrations and activities. Apart from their family history, patients in group A were clinically and biochemically indistinguishable from cases of type I (sporadic) PCT. Group B contained six families with the only previously described form of familial PCT (type II PCT) in which decreased erythrocyte uroporphyrinogen decarboxylase segregates as an autosomal dominant trait. These findings show that familial PCT is heterogeneous and suggest that inheritance contributes to the pathogenesis of at least some cases of type I PCT.

A geneticist's approach to psychiatric disease

The pattern of the genetics of psychiatric disease is various, in detail and in kind; one cannot always expect to find simple, trustworthy explanations of what are complex relationships. There will be some diseases, mostly of the disruptive type, that will prove to be Mendelian defects; but it would be idle to expect that of most. Many disorders will be elucidated only when the nub of the problem is better defined. Mindless application of standard genetic techniques devised for quite different purposes is no substitute for articulate speculation built on sound fact and cogent testing. In this respect genetic evidence is no different from that of physiology, pathology and pharmacology, which are perhaps less unfamiliar to readers than genetics. Finally, no answer has been found unless it deals in those terms in which the question first arose. If the topic of the genetic analysis is some psychosis, the final predicate must be a statement about the psychosis, not about some arbitrary abstraction from it.

Acquired and inherited porphyria: clinical and biochemical features

Inheritance in 30 cases of porphyria cutanea tarda (PCT) and their relatives was investigated. Seventeen families were studied using the clinical criteria, quantitation, and thin layer chromatography of urinary porphyrins. Thirteen families (13 propositus and 48 relatives) were investigated by using the above criteria and in vitro porphyrin biosynthesis by erythrocytes from delta-aminolevulinic acid. Three different types of PCT were identified: overt, subclinical, and latent. Among 61 members examined, 13 had overt PCT. In six families, ten members had subclinical PCT and six latent PCT showing that in these six families PCT was a hereditary disorder. In seven other families inheritance could not be demonstrated.

[Dysautonomic aspects of acute intermittent porphyria. Apropos of 6 cases]

The study of six patients with acute intermittent porphyria is reported. Clinical and biochemical studies have been performed during the long hospitalization of the patiets. The main disautonomic aspects were the arterial hypertension and the tachycardia in four patients, cardiac arrest in three patients and respiratory arrest in five patients. The cause of this problems is probably the involvment of the autonomic adrenergic system. The authors observed also three patients with hyponatremia probably resulting from inappropriate secretion of antidiuretic hormone. The prognosis of the acute intermittent porphyria is worse if the patients have disautonomic symptoms; three patients died and two had neurological sequalae (motor tetraparesis).

Porphyria cutanea tarda in three generations of a single family

We examined conjugal and blood relatives of one kindred for evidence of porphyria cutanea tarda. The disease was identified in eight family members in three generations. Four were classified as having overt porphyria cutanea tarda because of four criteria: photo-enhanced dermatosis; excessive urinary excretion of uroporphyrins; characteristic thin-layer chromatographic pattern of urinary porphyrins; and decreased activity of erythrocyte uroporphyrinogen decarboxylase. Two patients with excessive excretion of uroporphyrins or characteristic chromatograms, or both, and decreased uroporphyrinogen decarboxylase activity were classified as having subclinical porphyria cutanea tarda, and two with decreased uroporphyrinogen decarboxylase activity only were classified as having latent porphyria cutanea tarda. This study provides further evidence that prophyria cutanea tarda can be a familial disease inherited in an autosomal dominant fashion. We propose a reclassification of porphria cutanea tarda as an overt, subclinical or latent disorder.

Porphyria variegata and porphyria cutanea tarda in siblings: chemical and genetic aspects

A woman aged 54 was studied because of a severe acute porphyric (neurologic) relapse with clinical and chemical findings characteristic of porphyria variegata. During a family survey, her brother, aged 59, was found to have chemical abnormalities typical of porphyria cutanea tarda, without suggestion of neurologic manifestations. He had mild skin changes compatible with either of these forms of porphyria. The sister exhibited the protocoproporphyria of porphyria variegata, together with a large amount of fecal "x" porphyrin fraction, without demonstrable isocoproporphyrins. The brother had a uro-isocopro-type of porphyria in accord with the diagnosis of porphyria cutanea tarda, and quite at variance with the sister's findings. This occurrence of porphyria variegata and porphyria cutanea tarda in siblings is thus far unique. Certain hypotheses are considered in respect to genetic aspects of the differing prophyrias in this sibling pair.