Smoking and recurrent attacks of acute intermittent porphyria

Acute hepatic porphyrias-A guide for hepatologists

The acute hepatic porphyrias (AHPs) are a group of rare, inherited disorders of the heme biosynthesis pathway, usually manifesting with attacks of acute abdominal pain and other neurovisceral symptoms, with or without cutaneous manifestations. AHPs are characterized by the accumulation of porphyrin precursors, porphobilinogen, and/or aminolevulinic acid, in the blood. The diagnosis is often missed or delayed due to both inadequate testing and the improper use of available laboratory tests. In this review, we describe the various clinical presentations of the 4 AHPs, elucidate the approach to diagnosis, and provide recommendations for immediate and long-term management. We also describe the different complications that can occur with long-standing AHP, including the development of HCC. The AHPs are very treatable conditions, with excellent outcomes if diagnosed and treated early. A high index of suspicion for the presence of these disorders, along with accurate testing and timely treatment, will help reduce the burden of disease and prevent irreversible complications in patients with AHP.

Unusual Pain Disorders - What Can Be Learned from Them?

Pain is common in many different disorders and leads to a significant reduction in quality of life in the affected patients. Current treatment options are limited and often result in insufficient pain relief, partly due to the incomplete understanding of the underlying pathophysiological mechanisms. The identification of these pathomechanisms is therefore a central object of current research. There are also a number of rare pain diseases, that are generally little known and often undiagnosed, but whose correct diagnosis and examination can help to improve the management of pain disorders in general. In some of these unusual pain disorders like sodium-channelopathies or sensory modulation disorder the underlying pathophysiological mechanisms have only recently been unravelled. These mechanisms might serve as pharmacological targets that may also play a role in subgroups of other, more common pain diseases. In other unusual pain disorders, the identification of pathomechanisms has already led to the development of new drugs. A completely new therapeutic approach, the gene silencing, can even stop progression in hereditary transthyretin amyloidosis and porphyria, ie in pain diseases that would otherwise be rapidly fatal if left untreated. Thus, pain therapists and researchers should be aware of these rare and unusual pain disorders as they offer the unique opportunity to study mechanisms, identify new druggable targets and finally because early diagnosis might save many patient lives.

Lifestyle factors including diet and biochemical biomarkers in acute intermittent porphyria: Results from a case-control study in northern Norway

BACKGROUND

Lifestyle factors, including a low intake of carbohydrates, dieting, alcohol consumption, cigarette smoking and stress are some of the possible triggers of attacks in acute intermittent porphyria (AIP). The influence of lifestyle factors, including energy intake, diet and alcohol consumption on the biochemical disease activity in AIP and biochemical nutritional markers were examined.

METHODS

A case-control study with 50 AIP cases and 50 controls matched for age, sex and place of residence was performed. Dietary intake was registered using a food diary in 46 matched pairs. Symptoms, alcohol intake, stress and other triggering factors of the last AIP attack were recorded on questionnaires. Porphyrin precursors, liver and kidney function markers, vitamins, diabetogenic hormones and other nutritional biomarkers were analyzed by routine methods. The Wilcoxon matched-pairs signed rank test was used to compare the cases vs. controls. The Spearman's rank correlation coefficient was used on the cases.

RESULTS

Increasing total energy intake was negatively correlated with the biochemical disease activity. The intake of carbohydrates was lower than recommended, i.e., 40 and 39% of total energy intake in the AIP cases and controls, respectively. The plasma resistin level was significantly higher (p = .03) in the symptomatic than asymptomatic cases. Plasma insulin was lower in those with high porphobilinogen levels. The intake of sugar and candies were higher in the AIP cases with low U-delta aminolevulinic acid (ALA) levels (p = .04). Attacks were triggered by psychological stress (62%), physical strain (38%), food items (24%) and alcohol (32%) in the 34 symptomatic cases. Alcohol was used regularly by 88% of the cases (3.2 g ethanol/day) and 90% of the controls (6.3 g/day), but the intake was significantly lower in symptomatic than in asymptomatic cases (p = .045).

CONCLUSION

A high intake of energy, sugar and candies and a higher insulin level were associated with a lower biochemical disease activity. The resistin level was higher in the symptomatic than the asymptomatic cases. AIP patients drink alcohol regularly, but the intake was significantly lower in the symptomatic cases.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01617642.

Update review of the acute porphyrias

Acute porphyrias are rare inherited disorders due to deficiencies of haem synthesis enzymes. To date, all UK cases have been one of the three autosomal dominant forms, although penetrance is low and most gene carriers remain asymptomatic. Clinical presentation is typically with acute neurovisceral attacks characterised by severe abdominal pain, vomiting, tachycardia and hypertension. Severe attacks may be complicated by hyponatraemia, peripheral neuropathy sometimes causing paralysis, seizures and psychiatric features. Attacks are triggered by prescribed drugs, alcohol, hormonal changes, fasting or stress. The diagnosis is made by finding increased porphobilinogen excretion in a light-protected random urine sample. Management includes administration of intravenous human haemin and supportive treatment with non-porphyrinogenic drugs. A few patients develop recurrent attacks, a chronic illness requiring specialist management. Late complications include chronic pain, hepatocellular carcinoma, chronic renal failure and hypertension. In the UK, the National Acute Porphyria Service provides clinical advice and supplies haemin when indicated.

CpG sites associated with cigarette smoking: analysis of epigenome-wide data from the Sister Study

BACKGROUND

Smoking increases the risk of many diseases, and it is also linked to blood DNA methylation changes that may be important in disease etiology.

OBJECTIVES

We sought to identify novel CpG sites associated with cigarette smoking.

METHODS

We used two epigenome-wide data sets from the Sister Study to identify and confirm CpG sites associated with smoking. One included 908 women with methylation measurements at 27,578 CpG sites using the HumanMethylation27 BeadChip; the other included 200 women with methylation measurements for 473,844 CpG sites using the HumanMethylation450 BeadChip. Significant CpGs from the second data set that were not included in the 27K assay were validated by pyrosequencing in a subset of 476 samples from the first data set.

RESULTS

Our study successfully confirmed smoking associations for 9 previously established CpGs and identified 2 potentially novel CpGs: cg26764244 in GNG12 (p = 9.0 × 10-10) and cg22335340 in PTPN6 (p = 2.9 × 10-05). We also found strong evidence of an association between smoking status and cg02657160 in CPOX (p = 7.3 × 10-7), which has not been previously reported. All 12 CpGs were undermethylated in current smokers and showed an increasing percentage of methylation in former and never-smokers.

CONCLUSIONS

We identified 2 potentially novel smoking related CpG sites, and provided independent replication of 10 previously reported CpGs sites related to smoking, one of which is situated in the gene CPOX. The corresponding enzyme is involved in heme biosynthesis, and smoking is known to increase heme production. Our study extends the evidence base for smoking-related changes in DNA methylation.

Porphyric neuropathy

Porphyric neuropathy often poses a diagnostic dilemma; it is typically associated with the hepatic porphyrias, characterized by acute life-threatening attacks of neurovisceral symptoms that mimic a range of acute medical and psychiatric conditions. The development of acute neurovisceral attacks is responsive to environmental factors, including drugs, hormones, and diet. This chapter reviews the clinical manifestations, genetics, pathophysiology, and mechanisms of neurotoxicity of the acute hepatic porphyrias. While the etiology of the neurological manifestations in the acute porphyrias remains undefined, the main hypotheses include toxicity of porphyrin precursors and deficiency of heme synthesis. These hypotheses will be discussed with reference to novel experimental models of porphyric neuropathy.

Gene-environmental interactions: Lessons from porphyria

The porphyrias are uncommon, complex, and fascinating metabolic conditions, caused by deficiencies in the activities of the enzymes of the heme biosynthetic pathway. Two cardinal symptoms of the porphyrias are cutaneous photosensitivity and neurologic disturbances. Molecular analysis of gene defects has shown that there are multiple and heterogeneous mutations in each porphyria. Patients with symptomatic porphyria can suffer greatly, and, in rare cases, may die. While congenital porphyrias are inherited, other forms of porphyria occur as acquired diseases. In addition, not all gene carriers of inherited porphyrias develop clinical disease and there is a significant interplay between the gene defect and acquired or environmental factors. The variable response of porphyrias to acquired factors may, likely reflect genetic polymorphisms in drug metabolism. The lessons from acute hepatic porphyria, such as acute intermittent porphyria, are very useful in clarifying the complex nature of the clinical expression of metabolic disorders.

Porphyrias

Hereditary porphyrias are a group of eight metabolic disorders of the haem biosynthesis pathway that are characterised by acute neurovisceral symptoms, skin lesions, or both. Every porphyria is caused by abnormal function of a separate enzymatic step, resulting in a specific accumulation of haem precursors. Seven porphyrias are the result of a partial enzyme deficiency, and a gain of function mechanism has been characterised in a new porphyria. Acute porphyrias present with acute attacks, typically consisting of severe abdominal pain, nausea, constipation, confusion, and seizure, and can be life-threatening. Cutaneous porphyrias present with either acute painful photosensitivity or skin fragility and blisters. Rare recessive porphyrias usually manifest in early childhood with either severe cutaneous photosensitivity and chronic haemolysis or chronic neurological symptoms with or without photosensitivity. Porphyrias are still underdiagnosed, but when they are suspected, and dependent on clinical presentation, simple first-line tests can be used to establish the diagnosis in all symptomatic patients. Diagnosis is essential to enable specific treatments to be started as soon as possible. Screening of families to identify presymptomatic carriers is crucial to decrease risk of overt disease of acute porphyrias through counselling about avoidance of potential precipitants.

[Acute intermittent porphyria and chronic transaminase elevation]

Acute intermittent porphyria is an autosomal dominant inherited disorder resulting from a deficiency of porphobilinogen deaminase activity, the third enzyme in the heme biosynthesis pathway. This disease is uncommon, although the prevalence is higher in asymptomatic heterozygotic carriers; however, this prevalence is difficult to establish because of the absence of symptoms. Although acute intermittent porphyria is a multisystemic disease, its most common form of presentation is abdominal pain and neurological or mental symptoms, which can sometimes be due to precipitating factors such as reduced energy intake, smoking, alcohol, some drugs, and stress. Diagnosis can be made by testing urinary porphobilinogen levels, with subsequent measurement of enzyme activity and DNA testing. Treatment is based on prevention of porphyria attacks by avoiding precipitating factors and early administration of intravenous glucose or hemin therapy. We present the case of a patient diagnosed with acute intermittent porphyria based on study of chronic mild alanine aminotransferase (ALT) elevation.

Modern diagnosis and management of the porphyrias

Recent advances in the molecular understanding of the porphyrias now offer specific diagnosis and precise definition of the types of genetic mutations involved in the disease. Molecular diagnostic testing is powerful and very useful in kindred evaluation and genetic counselling when a disease-responsible mutation has been identified in the family. It is also the only way to properly screen asymptomatic gene carriers, facilitating correct treatment and appropriate genetic counselling of family members at risk. However, it should be noted that DNA-based testing is for the diagnosis of the gene carrier status, but not for the diagnosis of clinical syndrome or severity of the disease, e.g. an acute attack. For the diagnosis of clinically expressed porphyrias, a logical stepwise approach including the analysis of porphyrins and their precursors should not be underestimated, as it is still very useful, and is often the best from the cost-effective point of view.

Acute intermittent porphyria

Acute intermittent porphyria (AIP) is characterised by neurovisceral crises the most common clinical presentation of which is abdominal pain. It is an autosomal dominant condition with incomplete penetrance and is potentially life-threatening. The key point in management is to suspect and confirm the diagnosis as early as possible in order to treat the attack and to avoid inappropriate treatments which may exacerbate the crisis. In this chapter we briefly outline the haem biosynthetic pathway and how deficiencies in individual enzymes give rise to the different porphyrias. We then describe the clinical features and diagnosis of AIP, followed by a discussion of pathogenesis, highlighting advances in the molecular biology of AIP and introducing the debate as to whether neurovisceral crises might result from porphyrin precursor neurotoxicity or from haem deficiency. Finally we discuss management, including family screening, avoidance of triggering factors, analgesia, maintenance of a high calorie intake, and administration of haem derivatives.

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.

Serum organochlorines and urinary porphyrin pattern in a population highly exposed to hexachlorobenzene

BACKGROUND

Porphyria cutanea tarda (PCT) is caused by hexachlorobenzene (HCB) in several species of laboratory mammals, but the human evidence is contradictory. In a study among adults of a population highly exposed to HCB (Flix, Catalonia, Spain), the prevalence of PCT was not increased. We aimed at analysing the association of individual urinary porphyrins with the serum concentrations of HCB and other organochlorine compounds in this highly exposed population.

METHODS

A cross-sectional study on total porphyrins was carried out in 1994 on 604 inhabitants of the general population of Flix, older than 14 years. Of them, 241 subjects (comprising a random sample and the subgroup with the highest exposure) were included for the present study. The porphyrin profile was determined by high-pressure liquid chromatography. Serum concentrations of HCB, as well as common organochlorine compounds, were determined by gas chromatography coupled to electron capture detection.

RESULTS

Coproporphyrin I (CPI) and coproporphyrin III (CPIII) were the major porphyrins excreted, while uroporphyrins I and III were only detected in 2% and 36% of the subjects respectively, and heptaporphyrins I and III in 1% and 6%, respectively. CPI and CPIII decreased with increasing HCB concentrations (p < 0.05). This negative association was not explained by age, alcohol, smoking, or other organochlorine compounds. No association was found between uroporphyrin I and III excretion, nor heptaporphyrin excretion, and HCB. CPIII increased with smoking (p < 0.05).

CONCLUSION

HCB exposure in this highly exposed population did not increase urinary concentrations of individual porphyrins.

Renal symptomatology in patients with acute intermittent porphyria. A population-based study

OBJECTIVE

Can renal insufficiency in subjects with acute intermittent porphyria (AIP) be due solely to

DESIGN

A population-based study.

SUBJECTS

Subjects with AIP > or = 18 years of age (n = 386) in the four most northerly counties of Sweden.

INTERVENTIONS

Screening with creatinine clearance at 24 h. Patients below the lower reference level underwent a repeat clearance test and, if still low, also chromEDTA clearance.

RESULTS

286 (74%) subjects performed the creatinine clearance test and in 57 clearance was low; the second clearance proved normal in 23 who were then excluded. Eighteen subjects with other possible medical reasons for renal insufficiency, ethical reasons or refusing further examinations were also excluded. The 16 remaining subjects with no explanation for their renal insufficiency other than AIP were then studied in detail. All 14 women, mean age 52 years, and two uraemic men, 58 and 67 years, had manifest AIP. Twelve patients had hypertension (HT) and four were normotensive in spite of renal insufficiency. Histological findings of renal biopsies revealed diffuse glomerulosclerotic and interstitial changes with additional ischaemic lesions.

CONCLUSION

Protracted vasospasm in attacks of AIP may be a cause of renal lesions. This is discussed.

Chronic recurrent abdominal pain

Chronic recurrent abdominal pain remains a common medical and surgical problem, frequently dismissed as functional. Instead, these patients should be approached systematically, based on the pattern of recurrent abdominal pain. It is vital to seek out the potential cause of this type of chronic pain because specific and often curative treatment is available.

Hypertension and renal disease in patients with acute intermittent porphyria

OBJECTIVES

To assess the association between acute intermittent porphyria (AIP), hypertension and renal disease.

DESIGN

A population-based matched case-control study (1:4) in 50 AIP patients (manifest/latent 25/25), a retrospective study of all individuals who died between the years 1978 and 1990 (2122 including 33 with AIP) and a group of eight patients with severe AIP.

RESULTS

Hypertension was found in 56% of patients with manifest AIP, 33% of their controls (P = 0.041) and 16% of patients with latent AIP (P = 0.004). Renal disease was not more common in patients with AIP than in their controls. Three of the eight patients with severe recurrent AIP had impaired renal function, caused in one by systemic lupus erythematosus (SLE) nephritis. In the other two, no cause other than AIP could be found. In the mortality study, hypertension was registered in 68% of patients with manifest AIP compared to 21% of those with latent AIP (P = 0.008) but death from myocardial infarction and stroke was not more common. Uraemia was cited as the cause of death in 9.1% of AIP patients and 1.0% of those without AIP (P = 0.006).

CONCLUSIONS

Hypertension is more common in patients with manifest AIP than in those with latent AIP or control subjects. Renal disease may be due to hypertension, to AIP or to SLE. AIP may predispose to other renal diseases.

Biochemistry of porphyria

1. The porphyrias are a group of metabolic disorders arising from defects in the haem biosynthetic pathway. Most forms are inherited as Mendelian autosomal dominants, but some types are recessive and others acquired through exposure to porphyrinogenic drugs and chemicals. There is a linked group of diseases, which are not porphyrias, but have in common alterations of haem biosynthesis. 2. The processes of haem biosynthesis are now well understood and the molecular biology of the functions and dysfunctions in the porphyrias are currently an area of intensive investigation. 3. The acute porphyrias, Acute Intermittent Porphyria, Variegate Porphyria and Hereditary Coproporphyria are of most importance since attacks of these may be life-threatening. 4. These diseases that usually present with a neurovisceral attack are characterized by excess production of the porphyrin precursors, 5-aminolaevulinate and porphobilinogen because of lowered activity of Porphobilinogen deaminase. 5. A variety of factors may precipitate these attacks including various drugs, alcohol, smoking, dieting or fasting and variations in steroid hormone levels. 6. The non-acute porphyrias are largely dermatological conditions, which present clinically as cutaneous photosensitivity. The dermatological changes are caused by the photosensitizing properties of circulating porphyrins and are accompanied by systemic effects of these porphyrins.