Management of the acute porphyrias

Cutaneous porphyrias part II: treatment strategies

The porphyrias are diverse in pathophysiology, clinical presentation, severity, and prognosis, presenting a diagnostic and therapeutic challenge. Although not easily curable, the dermatological manifestations of these diseases, photosensitivity and associated cutaneous pathology, can be effectively prevented and managed. Sun avoidance is essential, and patient education regarding the irreversibility of photocutaneous damage is a necessary corollary. Beyond preventative measures, the care of fragile, vulnerable skin, and pain management, each of the porphyrias has a limited number of unique additional therapeutic options. Many of the treatments have been published only in small case series or anecdotal reports and do not have well-understood nor proven mechanisms of action. This article presents a comprehensive review of available therapeutic options and long-term management recommendations for the cutaneous porphyrias.

Assessing nutritional status of acute intermittent porphyria patients

BACKGROUND

Acute intermittent porphyria (AIP) is a metabolic disease of haem synthesis, whose haem precursors may accumulate in the body. A well-balanced diet may prevent the symptoms, so that porphyric patients should be monitored closely during therapy for possible complications concerning any progression of acute porphyria. The aim was to evaluate the nutritional status of patients with AIP and to assess their compliance with nutritional recommendations, comparing the findings with a control group and assessing any possible nutritional deficiency.

MATERIAL AND METHODS

Sixteen patients with AIP and a control group were evaluated by means of a lifestyle questionnaire, the Nutrition Screening Initiative checklist and a dietary questionnaire. The following diet quality indicators were calculated: animal and vegetal proteins, protein quality index, PUFA/SFA and MUFA + PUFA/SFA ratios, insoluble dietary fibre (DF)/total DF, soluble DF/total DF and insoluble DF/soluble DF ratios, thiamine, riboflavin and niacin density and the vitamin B6/protein ratio.

STATISTICAL METHODS

Differences in continuous variables were compared using the unpaired Student's t-test and the chi-square test for nonparametric variables. The odds ratio (OR) of malnutrition was also used.

RESULTS

Our patients showed a low intake of carbohydrates, a high lipid intake and very high protein intake, and accompanied by an inadequate intake of zinc, folic acid and tocopherol, increasing the risk of malnutrition for energy, Ca, Fe, Mg, K, folic acid and tocopherols.

CONCLUSIONS

The patients with AIP studied individually show an increased risk of malnutrition and, given the potential increase of oxidative stress in patients with porphyria, it is recommended that they should increase their intake of carbohydrates, minerals and antioxidant nutrients.

Anxiety and depression in the acute porphyrias

A previous study of self-rated psychosocial aspects in patients with acute porphyria found that depression, and particularly anxiety, is more common in porphyria patients than in the general population or general medical outpatient attenders. Nearly half of the sample (46%) reported at least some problem with anxiety and/or depression: anxiety caseness was 26% and depression caseness was 13%. This paper extends our previous observations and investigates further the associations between porphyria and anxiety, depression and general mental health in 90 patients (58 acute intermittent porphyria, 32 variegate porphyria). The findings of this study confirm that anxiety is raised in patients with acute intermittent porphyria and with variegate porphyria, in both males and females, compared to the normative population and, using a series of questionnaires exploring the physical and psychosocial features of anxiety, that this anxiety is experienced as a 'relatively stable personality trait', rather than a 'transitory emotional state' (i.e. intrinsic rather than secondary to the porphyria).

Adenoviral-mediated expression of porphobilinogen deaminase in liver restores the metabolic defect in a mouse model of acute intermittent porphyria

The aim of this study was to investigate the potential of gene therapy in the treatment of acute intermittent porphyria (AIP), a disorder caused by a partial deficiency of porphobilinogen deaminase (PBGD), the third enzyme in heme synthesis. The condition is biochemically characterized by accumulation of the porphyrin precursors 5-aminolevulinic acid (ALA) and porphobilinogen (PBG). Here we present the first experiments in vivo using adenoviral vectors to replace the deficient enzyme in the liver of an AIP mouse model. The use of adenoviral vector carrying the cDNA of luciferase in wild-type mice confirmed that transgene expression after intravenous administration was found mainly in liver. When PBGD-deficient mice were administered with adenoviral vector carrying the cDNA of mouse PBGD, the hepatic PBGD activity increased in a dose- and time-dependent manner. The highest activity was found 7 days after injection and remained high after 29 days. The expressed enzyme was shown to correct the metabolic defect in the PBGD-deficient mice as no accumulation of ALA or PBG occurred in plasma, liver, or kidney after induction of heme synthesis by phenobarbital. The study demonstrates that hepatic PBGD expression prevents the accumulation of porphyrin precursors, suggesting a future potential for gene therapy in AIP.

Porphyria and dementia: a case report

The porphyrias are a group of rare hereditary metabolic disorders where there is an excess formation and excretion of porphyrins or their precursors. Type IIA, acute intermittent porphyria (AIP), has an estimated prevalence of one to eight per 100,000 in the general population but is thought to have a higher prevalence in psychiatric patients. AIP can present with a variety of psychiatric symptoms, often misdiagnosed. Associated neuropathological changes including focal cerebral ischaemic lesions have been found. However, to our knowledge, no case of dementia and AIP has been described. We present the case of a 56 year old man with a five-year history of progressive cognitive decline, diagnosed with AIP at an advanced stage of dementia. Whether AIP contributed to the dementia or is a coincidental finding is unknown. However treatment of AIP in this case resulted in some improvement in the patient's cognitive state.