Porphyrin precursors and porphyrins in three patients with acute intermittent porphyria and end-stage renal disease under different therapy regimes.

Porphyrin precursors and porphyrins were measured in three patients with recurrent attacks of acute intermittent porphyria and end-stage renal disease (ESRD): two patients on hemodialysis and one on peritoneal dialysis. Plasma porphobilinogen (PBG) and porphyrins were considerably increased in the three patients. In a previous study, the mean urinary and plasma PBG/ALA ratio in biochemically active AIP patients with conserved renal function was 2.0 (normal 0.3) and plasma porphyrin levels were normal (< 10 nmol/L). In this study we show that the progression to ESRD was paralleled by an increase in urinary and plasma PBG/ALA ratio reaching levels above 6 and higher. Plasma porphyrin increased to levels above 1000 nmol/L causing cutaneous lesions resembling porphyria cutanea tarda. The porphyrin precursors were readily filtered by dialysis membranes but not the porphyrins. The development of kidney failure was a devastating complication in these AIP patients with chronic active disease, leading to unavoidable deterioration of peripheral veins, progression of peripheral neuropathy, dialysis treatment and secondary cutaneous lesions. The clinical course could not be reversed by medical treatment in any of the cases. Today, combined liver and kidney transplantation should be considered as a therapeutic option.

Porphyria in Sweden.

In a brief survey the work of Swedish porphyrinologists through time is presented, from the organic chemist Jakob Berzelius 1840 to the molecular biologists of today. The building up in Stockholm of a Swedish national competence centre for porphyria is touched upon and the emergence of a computerized national register on the porphyria gene carriers in the country described. Figures for the prevalences of the seven different forms of porphyria diagnosed in Sweden are given. The geographical distribution of gene mutation spectra is shown for the most frequent form, acute intermittent porphyria. The organisation at Porphyria Centre Sweden of its diagnostic and consultative services is described, as is the decentralized model for porphyria care applied in the form of a clinical network covering the long and sparsely populated country. The ideas and activities of the Swedish Porphyria Patients' Association are presented. Its focus on protection-by-information of the porphyria gene carrier against maltreatment in health service contacts, and against other exposures to environmental threats to his or her health, is discussed. The combined efforts of the national porphyria centre and the patients' association have resulted in early and accurate diagnosis of most of the porphyria gene carriers in the country. The information to the carriers and to the health service regarding the mechanisms of the diseases and the importance of avoiding exposure to disease triggering environmental factors have greatly reduced porphyric morbidity. In the case of the acute porphyrias, by this programme and after the introduction of heme arginate in the therapy, mortality in the acute phase has become extremely rare in Sweden. In contrast, probably due to greater awareness of the high risk for liver cancer in acute porphyrias the number of hepatoma cases diagnosed has increased. The current research activities at the Porphyria Centre which aim at finding ways to substitute the mutated gene in acute intermittent porphyria for an undamaged one, or to substitute the enzyme deficiency by administration of exogenously produced enzyme, are mentioned, as is the work to establish a reliable drug porphyrinogenicity prediction model for evidence based drug counselling.

[Prevention of acute intermittent porphyria is the best solution. Most important are early diagnosis and counseling]. / Bäst förebygga vid akut intermittent porfyri. Tidig diagnos och rådgivning till anlagsbäraren viktigast.

Recent mapping of acute intermittent porphyria (AIP) in Sweden has confirmed its very high prevalence in northern districts, though about fifty per cent of the gene carriers are to be found in the central and southern parts of the country. More than eighteen different AIP mutations are currently recognised in the Swedish kindreds. One mutations, evidently originating in northern Sweden, is predominant. As AIP is a pharmacogenetic disease, more than 200 substances being currently known to precipitate the neuropsychiatric symptoms, the greatest care is required in prescribing drugs to carriers of genetic predisposition to the disease. Guidelines are provided in the booklet. Drugs contraindicated in acute porphyria (Läkemedel farliga vid akut porfyri), jointly issued by the Swedish Porphyria Association and the Corporation of Swedish Pharmacists (Apoteksbolaget). Where doubt exists, specialists should be consulted since there are a number of factors that may contribute to an adverse reaction. Early diagnosis, preferably before puberty, and counselling are the cornerstones of management, and genetic analysis the diagnostic tool of choice, applicable in most families. In the symptomatic phase, glucose or haem arginate is effective in reversing the metabolic processes responsible for the exacerbation. Recently, the hepatic and late renal manifestations of the disease have been recognised, and early detection of the associated conditions is recommended. This includes monitoring for paraneoplastic prodromes of hepatocellular cancer.

[Porphyria--a metabolic mine field]. / Porfyri--minering i metabolismen.

The porphyrias, uncommon conditions often eluding diagnosis, extremely susceptible to inappropriate treatment and associated with severe late manifestations, are representative of the small groups of scarce and complex diseases that are difficult to manage without specialised resources. A network of offices with diagnostic and consultative support from a national specialist centre is probably the most cost effective way of meeting the patients' demands in terms of highly specialised medical experience coupled with close contact and continuity This approach, adopted by the Swedish Porphyria Centre, is based on well structured and regularly updated programmes for the management of porphyria patients.

Effects of administration of antioxidants in acute intermittent porphyria.

In order to elucidate the question of free radical involvement in acute porphyric crisis, antioxidants were administered to two acute intermittent porphyria patients with long-standing recurrent attacks. Clinical condition and urinary excretion of porphyrins and porphyrin precursors were monitored before, during and after an eight week therapy with daily doses of vitamin E, beta-carotene, ascorbic acid, selenium, vitamin Q, acetylcysteine, mannitol and carnitine. Blood cell trace element profiles were followed. The administration of the compound antioxidant formula was found not to further impair the clinical or biochemical conditions of the patients but the incidence of the recurrent crises or the severity of the symptoms were not positively affected. Aberrant blood cell trace element profiles with increased granulocyte manganese were normalized during treatment, on cessation of the therapy again resuming the abnormal pretreatment patterns, which may suggest an origin in oxidative stress. No correlation was observed between the concentration of granulocyte manganese and the excretion of 5-aminolaevulinic acid. Indications for participation of this porphyrin precursor in a radical generating process leading to generalized mitochondrial superoxide dismutase induction, as conceivably signalled by increased intracellular manganese, were thus not obtained. The failure to note a clinical response to antioxidant therapy may be due to factors dependent upon dosage of, or interaction between, the antioxidant compounds given, or on restricted bioavailability of the antioxidants at critical anatomical sites, and does not per se invalidate the model of acute porphyria as a hyperoxidative condition.

Pathogenic mechanisms of the acute porphyric attack: speculative roles of manganese associated enzymes.

The significantly increased concentrations of granulocyte manganese in subjects with AIP may be an indication of overexpression of manganese-associated enzymes. In this study we present further observations related to this phenomenon and speculate that this may provide a rational basis for hypotheses attempting to explain the pathogenesis of the acute attack of porphyria. Such hypotheses are advanced with regard to pyruvate carboxylase, mitochondrial superoxide dismutase and glutamine synthetase, three manganese-dependent enzymes associated with either ALA-generating or ALA-dependent processes. The metabolic impacts in acute porphyria of these enzymes would be functions of the current energy charge of the organism, and would thus explain the protecting and ameliorating effects of glucose in these conditions. Although granulocytes from AIP subjects have elevated manganese concentrations, this did not appear to be associated with increased activities of two enzymes assayed, pyruvate carboxylase or mitochondrial superoxide dismutase. However, enzyme activities in white blood cells do not necessarily represent the levels of catalytic activity in cell types involved in the phenotypic expression of porphyria. Thus it proposed that hypotheses along these new lines of thinking are not flawed by the apparently missing correlations, and should not be therefore discarded. The possible roles of manganese-associated enzymes in the mechanisms behind the acute porphyric attack are discussed in some detail in the paper.

Markers for vulnerability in acute porphyria. A hypothesis paper.

Previously symptomatic and permanently asymptomatic carriers of a gene mutation for acute intermittent porphyria as well as matched controls were screened with regard to a series of variables of possible relevance to the development of porphyric symptoms. The basis for the study was a concept of acute porphyria as a condition of a permanent system overload of oxidative stress, with long term effects on hepatic and renal tissue, and with instances of periodic overload of free radicals giving rise to acute neurologic involvement. Leukocyte concentrations of manganese, calcium, iron and zinc, as well as erythrocyte calcium differed between the groups, acute intermittent porphyria gene carriers, irrespective of previous porphyric illness, showing significantly higher levels than the controls. Manganese was found to be the most discriminative component of all the 78 variables investigated, accounting for about 98 per cent of the variance between the groups. An increment, by a factor of four, in cellular manganese is suggestive of an increase, in acute intermittent porphyria, of a manganese associated enzyme, e.g. glutamine synthetase, pyruvate carboxylase or mitochondrial superoxide dismutase. The best fit into the model considered is provided by a theory focused on superoxide dismutase, induced in response to superoxide anion radical produced from aminolaevulinic acid. In porphyria gene carriers seemingly resistant to porphyric manifestations, an increase in potentially prooxidant cellular iron is matched by a proportional increment in manganese, i.e. presumably by a corresponding mitochondrial superoxide dismutase induction. This mechanism is not operative in porphyric individuals prone to development of neuropsychiatric symptoms. In acute intermittent porphyria with a history of porphyric illness there is a positive correlation between erythrocyte manganese and serum folate and a negative correlation between leukocyte ferrochelatase activity and serum cobalamin concentration. This may mirror a role of the cobalamin-folate system in the acute porphyric process.

Liver transplantation in a boy with acute porphyria due to aminolaevulinate dehydratase deficiency.

The clinical and biochemical outcome of a liver transplantation in a seven-year-old boy with acute porphyria due to aminolaevulinate dehydratase deficiency is described. Before transplantation standard liver function tests were normal and the rationale for transplantation was that the new liver would reduce the metabolic disturbance and thus avert the porphyric symptoms. During the year after the transplantation, the functioning of the new liver has been excellent. Basal excretion of porphyrin and porphyrin precursors has remained unchanged but, with the new liver transplant the patient has been able to withstand several porphyrinogenic challenges without increasing the excretion. Episodes of neurological and respiratory crises may have been due to persistent porphyric vulnerability. Alternatively, two early attacks may have been caused by neurotoxic effects of cyclosporin in combination with the existing damage to nervous tissue.

Alcoholic beverages in acute porphyria.

Alcohol consumption habits and the clinical consequences of intake of alcoholic beverages were examined in 254 individuals with a diagnosis of acute intermittent porphyria or variegate porphyria, using a questionnaire. The study failed to demonstrate a connection between the amount of ethanol consumed, or the frequency of ingestion, and the development of symptoms of acute porphyria, other than in extreme consumption patterns. It was concluded that agents in alcoholic beverages other than ethanol play important roles in precipitating the porphyric symptoms. A majority of the individuals were able to identify alcoholic beverages that were less well tolerated and those that were better tolerated. The results suggest that polyphenolic compounds and 3 to 5 carbon chain hydrophobic alcohols may be responsible for the induction of clinical symptoms in acute porphyria by some alcoholic beverages. On the basis of these findings advice is proposed on alcohol counseling in inducible porphyria.