Familial and Sporadic Porphyria Cutanea Tarda: Characterization and Diagnostic Strategies

Practical recommendations for biochemical and genetic diagnosis of the porphyrias

The porphyrias are a group of rare inborn errors of metabolism associated with various clinical presentations and long-term complications, making them relevant differential diagnoses to consider for many clinical specialities, especially hepatologists, gastroenterologists and dermatologists. To diagnose a patient with porphyria requires appropriate biochemical investigations, as clinical features alone are not specific enough. Furthermore, it is important to be aware that abnormalities of porphyrin accumulation and excretion occur in many other disorders that are collectively far more common than the porphyrias. In this review, we provide an overview of porphyria-related tests with their strengths and limitations, give recommendations on requesting and diagnostic approaches in non-expert and expert laboratories for different clinical scenarios and discuss the role of genetic testing in the porphyrias. To diagnose porphyria in a currently symptomatic patient requires analysis of biochemical markers to demonstrate typical patterns of haem precursors in urine, faeces and blood. The use of genomic sequencing in diagnostic pathways for porphyrias requires careful consideration, and the demonstration of increased porphyrin-related markers is necessary prior to genomic testing in symptomatic patients. In the acute porphyrias, genomic testing is presently a useful adjunct for genetic counselling of asymptomatic family members and the most common cutaneous porphyria, porphyria cutanea tarda, is usually a sporadic, non-hereditary disease. Getting a correct and timely porphyria diagnosis is essential for delivering appropriate care and ensuring best patient outcome.

Systematic review of the prevalence and incidence of the photodermatoses with meta-analysis of the prevalence of polymorphic light eruption

Information about the prevalence of photodermatoses is lacking, despite their substantial impact on life quality. Our objective was to systematically review the literature to establish what is known regarding prevalence and incidence of photodermatoses. We searched Medline, CINAHL and Embase from inception to 2021 to identify original population-based studies in English literature reporting the prevalence and/or incidence of photodermatoses. Information was extracted according to geographical location and risk of bias was assessed using a 10-point risk of bias tool for prevalence studies. Primary outcome was the population prevalence of photodermatoses. Prevalence data for polymorphic light eruption (PLE) were used to calculate the global pooled prevalence of PLE. Twenty-six studies were included; 15 reported prevalence of photodermatoses based on samples of the general population and 11 on prevalence and/or incidence from national and international registry data. The general population studies involved PLE (nine studies), unspecified photosensitivity (2), actinic prurigo (2), juvenile spring eruption (1), chronic actinic dermatitis (1) and variegate porphyria (1), while registry studies reported on cutaneous porphyrias and genophotodermatoses (nine and two studies, respectively). Worldwide the prevalence of PLE between countries ranged from 0.65% (China) to 21.4% (Ireland). The pooled estimated prevalence of PLE was 10% (95% CI 6%-15%) among the general population (n = 19,287), and PLE prevalence increased with distance from the equator (r = 0.78, p < 0.001). While several photodermatoses are rare, photosensitivity can be prevalent at wide-ranging world locations, including Egypt where photosensitivity was found in 4% of children and 10% of adults. This study showed that PLE is highly prevalent in many populations and that its prevalence shows a highly significant correlation with increasing northerly or southerly latitude. Available population-based studies for photodermatoses suggest they can be prevalent at a range of world locations; more attention is required to this area.

Porphyria cutanea tarda and patterns of long-term sick leave and disability pension: a 24-year nationwide matched-cohort study

BACKGROUND

Porphyria cutanea tarda (PCT) is a skin disorder caused by a defect in the liver enzyme uroporphyrinogen decarboxylase and is associated with hepatitis C virus infection, high alcohol intake, smoking and iron overload. Data on the long-term morbidity of PCT is lacking.

METHODS

We conducted a nationwide matched cohort study over a 24-year period. The study sample included 534 persons aged 18-67 years with a biochemically confirmed PCT diagnosis and a sample of 21,360 persons randomly selected from the working age population, matched on age, sex and educational attainment. We investigated if persons with sporadic and familial PCT had an increased risk of long-term sick leave (LTSL) or disability pension. We further assessed risk before (pre-PCT), during (during-PCT) and after (post-PCT) the typical period of first onset to diagnosis, treatment and remission.

RESULTS

Overall, persons with PCT had a 40% increased risk (hazard ratio [HR] = 1.4, 95% confidence interval [CI] = 1.3, 1.5) of LTSL and a 50% increased risk (HR = 1.5, CI = 1.3, 1.7) of disability pension. Risk of disability pension was increased pre-PCT (HR = 1.3, CI 1.3 (1.0, 1.6), during-PCT (HR 1.5, CI 1.0, 2.2) and post-PCT (HR = 2.0, CI 1.5, 2.6). For LTSL, risk was increased pre-PCT (HR = 1.3, CI 1.1, 1.4) and during-PCT (HR = 1.5, CI 1.1, 2.1), but not post-PCT. Risk was greatest in persons with sporadic than familial PCT. Diagnostic reasons for disability pension that were increased compared to matched controls were PCT or skin disease in 11 of 199 cases (PCT: n = 7, incident rate ratios [IRR] = 49.2, CI = 38.8, 62.4; diseases of the skin and subcutaneous tissue, n = 4, IRR = 4.2, CI = 1.6, 11.0). The vast majority of diagnostic reasons for accessing disability pension were related to comorbidities, PCT susceptibility factors and more general health issues such as: malignant neoplasms (n = 12, IRR = 2.4, CI = 1.4, 4.2), substance and alcohol dependence (n = 7, IRR = 5.0, CI = 2.5, 10.1), neurotic and mood-disorders (n = 21, IRR = 1.7, CI = 1.1, 2.6), and diseases of the musculoskeletal system and connective tissue (n = 71, IRR = 2.5, CI = 1.9, 3.2).

CONCLUSIONS

Persons with PCT have an increased risk of LTSL and disability pension indicating significant morbidity in this patient group. Appropriate long-term follow-up and monitoring for relapses and co-morbid diseases are recommended.

Evolution of HCV associated porphyria cutanea tarda after HCV sustained virologic response by direct acting antivirals

OBJECTIVES

Porphyria cutanea tarda (PCT) is common and usually associated with HCV chronic infection and HFE polymorphisms. Since DAA IFN-free regimens availability, SVR for HCV is nearly a constant and we wonder whether HCV SVR determine PCT evolution.

METHODS

Retrospective observational study including patients with HCV associated PCT from the Gastroenterology and Infectious Diseases Departments at our Hospital, treated with DAA (Apr/2015-Apr/2017). Clinical variables of PCT were collected at PCT diagnosis, after PCT treatment, before DAA use and after SVR achievement. UROD activity and C282Y/H63D polymorphisms were registered. SPSS 22.0.

RESULTS

13 HCV-PCT patients included: median age 52.5 years; 4 females; 8 HCV/HIV co-infected (all on undetectable viral load). Classical PCT factors: 12 smoked, 9 alcohol abuse, 6 former IDU. 10 type I PCT and 1 type II PCT. HFE polymorphism: 2 cases with C282Y/H63D; H63D polymorphism in 8. PCT manifestations resolved with PCT treatment in 4 patients, almost completely in 7 patients, 1 patient referred stabilization and one worsened. After DAA treatment all the residual lesions resolved, what always led to specific treatment interruption.

CONCLUSIONS

Our series of cases of HCV-associated PCT shows that SVR after DAA treatment leads to PCT resolution. Porphyrin levels are not needed after ending PCT specific treatment interruption when there are no residual skin lesions in HCV-associated PCT.

Laboratory Diagnosis of Porphyria

Porphyrias are a group of diseases that are clinically and genetically heterogeneous and originate mostly from inherited dysfunctions of specific enzymes involved in heme biosynthesis. Such dysfunctions result in the excessive production and excretion of the intermediates of the heme biosynthesis pathway in the blood, urine, or feces, and these intermediates are responsible for specific clinical presentations. Porphyrias continue to be underdiagnosed, although laboratory diagnosis based on the measurement of metabolites could be utilized to support clinical suspicion in all symptomatic patients. Moreover, the measurement of enzymatic activities along with a molecular analysis may confirm the diagnosis and are, therefore, crucial for identifying pre-symptomatic carriers. The present review provides an overview of the laboratory assays used most commonly for establishing the diagnosis of porphyria. This would assist the clinicians in prescribing appropriate diagnostic testing and interpreting the testing results.

Iatrogenic Iron Overload Causing Porphyria Cutanea Tarda in a Patient With a Rare Nonsense Heterozygous UROD Gene Mutation

Porphyria cutanea tarda (PCT) is a rare dermatologic condition characterized by blistering of sun-exposed surfaces and elevated hepatic enzymes. It may infrequently occur as the primary presentation of underlying hemochromatosis. A 61-year-old female with anemia caused by chronic kidney disease and end-stage renal disease on hemodialysis presented with a bullous rash on her hands with associated pruritus. The rash worsened despite conservative treatment. An initial biopsy demonstrated a pauci-inflammatory cell-poor subepidermal cleft. Subsequent workup revealed elevated serum and urine porphyrins, confirming a diagnosis of PCT. Additionally, her skin was darkened and ferritin was elevated. MRI of the liver demonstrated iron overload with genetic testing negative for C282Y or H63D mutations, supporting a diagnosis of secondary hemochromatosis. Further genetic testing revealed that the patient had a rare heterozygous nonsense mutation of the uroporphyrinogen decarboxylase (UROD) gene, for a sequence variant designated c.616C>T, which is predicted to result in premature protein termination (p.Gln206*). PCT occurs due to decreased function of UROD, leading to accumulation of porphyrins causing dermatologic manifestations and liver injury. UROD is inactivated in an iron-dependent process, explaining the mechanistic link between hemochromatosis and PCT.

Health-related quality of life in porphyria cutanea tarda: a cross-sectional registry based study

BACKGROUND

Porphyria cutanea tarda (PCT) is a rare, photosensitive disease characterized by skin fragility and blistering on sun-exposed areas. There is little previous research on how this condition affects health-related quality of life (HRQoL) and to the best of our knowledge this is the largest sample of PCT patients surveyed about their HRQoL. The aims of this study were to describe HRQoL, symptoms, susceptibility factors, disease activity and treatment in patients with PCT, and investigate the associations between these factors.

METHODS

This is a cross-sectional, retrospective study based on patient-reported outcome and laboratory data. The Norwegian Porphyria Centre diagnoses all patients with PCT in Norway, all of whom are invited to participate in the Norwegian Porphyria Registry. Between December 2013-2015, 111 patients received a postal questionnaire and invitation to participate.

RESULTS

Sixty-eight persons responded, with seven being excluded due to prolonged response time or missing information, resulting in 61 participants in the final analyses (55%). Median age was 60 years and 33 were female. We found a moderate negative relationship between the type and localisation of PCT symptoms and both mental (r = -.354 p < 0.01) and physical (r = -.441, p < 0.01) aspects of HRQoL. Participants who had started treatment when answering the questionnaire reported significantly better physical functioning and less bodily pain than those who had not started treatment. We did not observe an association between biochemical markers of disease activity and symptoms or HRQoL. Itching, a symptom that has received little attention in PCT was reported by 59% of the participants.

CONCLUSIONS

Our results show that reduced HRQoL is associated with more symptoms and not having started treatment. PCT is a rare disease, and there is a need for the development of best-practice guidelines to facilitate good patient care.

Porphyria cutanea tarda increases risk of hepatocellular carcinoma and premature death: a nationwide cohort study

Background

Porphyria cutanea tarda (PCT) is a skin disorder originating from a deficit of the liver enzyme uroporphyrinogen decarboxylase. PCT may be a risk factor for hepatocellular carcinoma (HCC) and other cancers, but the evidence is unclear. We aimed to investigate cancer and premature mortality risk in persons with PCT.

Methods

The cohort study consisted of all Norwegian residents from 18 years between 2000 and 2016 (n = 5.4 million). 612 persons with PCT, and all cancer diagnoses and causes of death were identified through record linkage between national registries. Hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) were adjusted for age, sex, education and calendar years. We additionally compared persons with PCT to persons with a history of chronic alcohol abuse (n = 30,468).

Results

Persons with PCT were more likely to be diagnosed with HCC [adjusted HR (aHR) = 19.7, CI = 8.8–44.0) and gallbladder and biliary tract cancer (aHR = 6.8, CI = 2.2–21.0) than the reference population. A moderate increased risk for HCC (aHR = 3.1, CI = 1.2–7.7) and gallbladder and biliary tract cancer (aHR = 4.0, CI = 1.1–14.4) remained when compared to persons with a history of chronic alcohol abuse. Additionally, compared to the reference population, persons with PCT had an increased risk of premature death (aHR = 1.5, CI = 1.2–1.7), due to the following causes of death: malignant neoplasms (aHR = 1.4, CI = 1.0–1.9), diseases of the liver (HR = 5.5, CI = 2.5–12.2), and drug and alcohol overdose (HR = 9.9, CI = 4.7–20.8).

Conclusions

Persons with PCT had an increased risk of HCC and cancer of the gallbladder and biliary tract, as well as premature death. Although most of our findings can likely be explained by common lifestyle risk factors, something inherent in PCT may contribute to the development of HCC.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1051-3) contains supplementary material, which is available to authorized users.

Experience in management of porphyria cutanea tarda in a tertiary referral Brazilian hospital from 2002 to 2017

BACKGROUND

Porphyria cutanea tarda (PCT) is the most common porphyria worldwide. The known acquired precipitating factors that induce PCT include alcoholism, hepatitis C virus infection, human immunodeficiency virus infection, and estrogen intake. Hereditary hemochromatosis is considered an inherited risk factor. The aim of this study was to describe and analyze precipitating factors and family history, with emphasis on PCT management.

METHODS

A retrospective study of 87 patients with PCT was conducted between January 2002 and December 2017.

RESULTS

A male predominance of 1.8 : 1 was found. The median age at diagnosis was 49 years (range 18-71). Family history of PCT was observed in 19.5% of patients. Two or more acquired precipitating factors were present in 42.5%. Patients were treated with antimalarial monotherapy (72.4%), antimalarial combined with phlebotomy (22.9%), and only with phlebotomy (4.6%). Acquired precipitating factors and inherited factors were not associated with treatment group. There was a difference in 24 h-UP normalization rate between treatment groups; combined therapy takes longer than antimalarial monotherapy, 38 months versus 15 months, respectively (CI 95%, 6.5-63.5 vs. 12.9-17) (log-rank test, P = 0.004).

CONCLUSION

Precipitating factors did not seem to be associated with treatment choice; however, all acquired and inherited precipitating factors should be investigated, and the choice between phlebotomy and/or antimalarials should be individualized. All dermatologists treating PCT patients should observe transferrin saturation and ferritin levels to search for underlying hereditary hemochromatosis.

[The cutaneous porphyrias]

The porphyrias are a group of metabolic disorders resulting from an innate abnormality in haem biosynthesis, and the clinical settings of which vary according to the genetic enzyme abnormality in question. These are genetic disorders with autosomal dominant or recessive inheritance of varying penetrance, and whose clinical expression differs according to the preferential location of haem precursors. Different classifications have been proposed according to genetic inheritance, the enzyme anomaly at issue, and clinical expression. The clinical classification distinguishes between acute porphyria (acute intermittent porphyria, porphyria variegata, hereditary coproporphyria), bullous cutaneous porphyrias (porphyria cutanea tarda, porphyria variegata and hereditary coproporphyria), painful photosensitive acute cutaneous porphyrias (erythropoietic protoporphyria and X-linked dominant protoporphyria), and rare recessive porphyrias (congenital erythropoietic porphyria, Doss porphyria, hepatoerythropoietic porphyria and harderoporphyria). Treatment depends on the clinical expression of the disorder.

Porphyria cutanea tarda: an intriguing genetic disease and marker

Porphyrias are a group of intriguing genetic diseases of the heme pathway, of which porphyria cutanea tarda (PCT) is the most common. Resulting from a defect in enzymes in the porphyria pathway, PCT has been linked to several conditions. Recent studies have demonstrated a change in thinking regarding the human immunodeficiency virus (HIV) and development of PCT. The exacerbation of PCT with contraction of HIV is now believed to result from coinfection from the hepatitis C virus (HCV). Blistering of sun-exposed skin, a classic presenting sign of PCT, is not exclusive to the condition. Cutaneous findings must also trigger physicians to consider additional types of porphyrias, such as variegate porphyria. The diagnosis of pseudoporphyria, which does not result from enzymatic absence, must be considered in patients with photosensitivity and cutaneous bullae. Recent health food trends, such as chlorophyll, have been linked to pseudoporphyria. PCT is a serious condition in which accurate diagnosis is necessary for appropriate management.

[Porphyria cutanea tara]

Porphyria cutanea tara (PCT) has a prevelance of about 40 new diagnoses per 1 million people per year and is the most frequently occurring type of porphyria worldwide. Inhibition of the uroporphyrinogen decarboxylase (UROD) is the main cause of the disease, which can be the result of a heterozygous or homozygous mutation of the UROD gene; however, xenobiotics or other diseases may play an important role for the precipitation of the disease. Risk factors include alcohol, estrogen, iron overload, and hemochromatosis, hepatitis C or poisoning, e.g., with polyhalogenated aromatic compounds such as hexachlorobenzene. Signs and symptoms are blisters, skin fragility, erosions hyperpigmentation, sclerodermoid plaques. Therapy includes sun protection, prevention of risk factors, phlebotomy, and chloroquine.

Porphyria Diagnostics-Part 1: A Brief Overview of the Porphyrias

Porphyria diseases are a group of metabolic disorders caused by abnormal functioning of heme biosynthesis enzymes and characterized by excessive accumulation and excretion of porphyrins and their precursors. Precisely which of these chemicals builds up depends on the type of porphyria. Porphyria is not a single disease but a group of nine disorders: acute intermittent porphyria (AIP), hereditary coproporphyria (HCP), variegate porphyria (VP), δ-aminolevulinic acid dehydratase deficiency porphyria (ADP), porphyria cutanea tarda (PCT), hepatoerythropoietic porphyria (HEP), congenital erythropoietic porphyria (CEP), erythropoietic protoporphyria (EPP), and X-linked protoporphyria (XLP). Each porphyria results from overproduction of heme precursors secondary to partial deficiency or, in XLP, increased activity of one of the enzymes of heme biosynthesis. Taken together, all forms of porphyria afflict fewer than 200,000 people in the United States. Based on European studies, the most common porphyria, PCT, has a prevalence of 1 in 10,000, the most common acute porphyria, AlP, has a prevalence of ∼1 in 20,000, and the most common erythropoietic porphyria, EPP, is estimated at 1 in 50,000 to 75,000. CEP is extremely rare, with prevalence estimates of 1 in 1,000,000 or less. Only six cases of ADP are documented. The current porphyria literature is very exhaustive and a brief overview of porphyria diseases is essential in order for the reader to better appreciate the relevance of this area of research prior to undertaking biochemical diagnostics procedures. This unit summarizes the current knowledge on the classification, clinical features, etiology, pathogenesis, and genetics of porphyria diseases.

A skin disease, a blood disease or something in between? An exploratory focus group study of patients' experiences with porphyria cutanea tarda

Background

Porphyria cutanea tarda (PCT) is characterized by fragile skin with blistering on sun-exposed areas. Symptoms typically develop in late adulthood and can be triggered by iron overload, alcohol intake, oestrogens and various liver diseases. Treatment consists of phlebotomy to reduce iron, or increasing urinary porphyrin excretion by administering chlorochin. To optimize patient care, health personnel need to understand the subjective experiences of PCT.

Objectives

To explore the experiences of persons with PCT with regard to symptoms, treatment, follow-up and prevention of the disease.

Methods

Interpretive description was used as a qualitative approach. Twenty-one participants attended three focus groups. All participants had experienced PCT symptoms during the last 5 years.

Results

Participants' experiences varied from trivializing symptoms and fragile skin to what was described as a desperate situation, with huge blisters, skin falling off and feeling as if one was in a ‘horror movie’. For some, itching was very troublesome, preventing sleep and delaying skin healing. In managing PCT a shift in focus from skin to blood was described. PCT was perceived as a chronic and systemic disease causing a range of health problems. Strategies for preventing symptoms ranged from doing nothing to frequent controls and check-ups.

Conclusions

Participants had a systemic perception of PCT, and a tendency to attribute a range of health problems to the condition. This study adds insight into the experiences patients have with PCT.

Cutaneous porphyrias part I: epidemiology, pathogenesis, presentation, diagnosis, and histopathology

The porphyrias are a group of disorders characterized by defects in the heme biosynthesis pathway. Many present with skin findings including photosensitivity, bullae, hypertrichosis, and scarring. Systemic symptoms may include abdominal pain, neuropsychiatric changes, anemia, and liver disease. With advances in DNA analysis, researchers are discovering the underlying genetic causes of the porphyrias, enabling family members to be tested for genetic mutations. Here we present a comprehensive review of porphyria focusing on those with cutaneous manifestations. In Part I, we have included the epidemiology, pathogenesis, presentation, diagnosis, and histopathology. Treatment and management options will be discussed in Part II.

Role of genetic testing in the management of patients with inherited porphyria and their families

The porphyrias are a group of mainly inherited metabolic conditions that result from partial deficiency of individual enzymes in the haem biosynthesis pathway. Clinical presentation is either with acute neurovisceral attacks, skin photosensitivity or both, and is due to overproduction of pathway intermediates. The primary diagnosis in the proband is based on biochemical testing of appropriate samples, preferably during or soon after onset of symptoms. The role of genetic testing in the autosomal dominant acute porphyrias (acute intermittent porphyria, hereditary coproporphyria and variegate porphyria) is to identify presymptomatic carriers of the family specific pathogenic mutation so that they can be counselled on how to minimize their risk of suffering an acute attack. At present the additional genetic factors that influence penetrance are not known, and all patients are treated as equally at risk. Genetic testing in the erythropoietic porphyrias (erythropoietic protoporphyria, congenital erythropoietic porphyria and X-linked dominant protoporphyria) is focused on predictive and preconceptual counselling, prenatal testing and genotype-phenotype correlation. Recent advances in analytical technology have resulted in increased sensitivity of mutation detection with success rates of greater than 90% for most of the genes. The ethical and consent issues are discussed. Current research into genetic factors that affect penetrance is likely to lead to a more refined approach to counselling for presymptomatic gene carriers.

Sun, iron, alcohol and intrinsic liver disease: a recipe for failure

A 62-year-old Caucasian woman, with remote history of painful skin blistering and hypertrichosis, recent history of travel to Mexico and increased alcohol consumption, presented with progressively worsening jaundice and fatigue. Physical examination was remarkable for severe generalised jaundice, scleral icterus and erythematous facial blistering and scarring. Laboratory workup revealed markedly elevated total and direct bilirubin, mildly elevated transaminases, severe iron overload and increased urine coproporphyrin. Porphyria cutanea tarda was diagnosed, and she was treated with supportive measures including hydration and alcohol cessation. Pathology of her liver demonstrated mild iron overload and severe fatty infiltration. Hospital follow-up revealed complete resolution of jaundice and fatigue and near-normalisation of liver function tests.

Establishing a network of specialist Porphyria centres - effects on diagnostic activities and services

BACKGROUND

The porphyrias are a heterogeneous group of rare metabolic diseases. The full spectrum of porphyria diagnostics is usually performed by specialized porphyria laboratories or centres. The European Porphyria Initiative (EPI), a collaborative network of porphyria centres formed in 2001, evolved in 2007 into the European Porphyria Network (EPNET), where participating centres are required to adhere to agreed quality criteria. The aim of this study was to examine the state and distribution of porphyria diagnostic services in 2009 and to explore potential effects of increased international collaboration in the field of these rare diseases in the period 2006-2009.

METHODS

Data on laboratory, diagnostic and clinical activities and services reported to EPI/EPNET in yearly activity reports during 2006 through 2009 were compared between reporting centres, and possible time trends explored.

RESULTS

Thirty-five porphyria centres from 22 countries, five of which were non-European associate EPNET members, filed one or more activity reports to EPI/EPNET during the study period. Large variations between centres were observed in the analytical repertoire offered, numbers of analyses performed and type and number of staff engaged. The proportion of centres fulfilling the minimum criteria set by EPNET to be classified as a specialist porphyria centre increased from 80% to 94% during the study period.

CONCLUSIONS

Porphyria services are unevenly distributed, and some areas are probably still lacking in specialized porphyria services altogether. However, improvements in the quality of diagnostic services provided by porphyria centres participating in EPI/EPNET were observed during 2006 through 2009.

Molecular analysis of the UROD gene in 17 Argentinean patients with familial porphyria cutanea tarda: characterization of four novel mutations

Porphyria cutanea tarda (PCT) is caused by decreased activity of uroporphyrinogen decarboxylase (UROD) in the liver. The disease usually occurs in adulthood and is characterized by cutaneous photosensitivity, hyperpigmentation, skin fragility and hypertrichosis, due to the accumulation of porphyrins produced by oxidation of uroporphyrinogen and other highly carboxylated porphyrinogens overproduced as a result of the enzyme deficiency. PCT is generally sporadic, but about 20-30% of patients have familial-PCT (F-PCT) which is associated with heterozygosity of mutations in the UROD gene. In the present study we have found the molecular defect in seventeen unrelated Argentinean patients with F-PCT, identifying a total of eleven UROD gene mutations: four novel and seven previously described. The novel mutations were: a guanine insertion at the 5' splice junction of intron 2, a three nucleotide deletion causing the lost of valine 90, a deletion of 22 bp in exon 6 and a deletion of part of the polyadenylation signal. Prokaryotic expression studies showed that the novel amino acid deletion resulted in an inactive protein. Mutations c.10insA and p.M165R, previously found in Argentinean patients, were recurrent in this study; they are the most frequent in Argentina accounting for 40% of the mutant alleles characterized to date.

European Specialist Porphyria Laboratories: Diagnostic Strategies, Analytical Quality, Clinical Interpretation, and Reporting As Assessed by an External Quality Assurance Program

BACKGROUND

The porphyrias are a group of rare metabolic disorders whose diagnosis depends on identification of specific patterns of porphyrin precursor and porphyrin accumulation in urine, blood, and feces. Diagnostic tests for porphyria are performed by specialized laboratories in many countries. Data regarding the analytical and diagnostic performance of these laboratories are scarce.

METHODS

We distributed 5 sets of multispecimen samples from different porphyria patients accompanied by clinical case histories to 18–21 European specialist porphyria laboratories/centers as part of a European Porphyria Network organized external analytical and postanalytical quality assessment (EQA) program. The laboratories stated which analyses they would normally have performed given the case histories and reported results of all porphyria-related analyses available, interpretative comments, and diagnoses.

RESULTS

Reported diagnostic strategies initially showed considerable diversity, but the number of laboratories applying adequate diagnostic strategies increased during the study period. We found an average interlaboratory CV of 50% (range 12%–152%) for analytes in absolute concentrations. Result normalization by forming ratios to the upper reference limits did not reduce this variation. Sixty-five percent of reported results were within biological variation–based analytical quality specifications. Clinical interpretation of the obtained analytical results was accurate, and most laboratories established the correct diagnosis in all distributions.

CONCLUSIONS

Based on a case-based EQA scheme, variations were apparent in analytical and diagnostic performance between European specialist porphyria laboratories. Our findings reinforce the use of EQA schemes as an essential tool to assess both analytical and diagnostic processes and thereby to improve patient care in rare diseases.

Excess risk of adverse pregnancy outcomes in women with porphyria: a population-based cohort study

The porphyrias comprise a heterogeneous group of rare, primarily hereditary, metabolic diseases caused by a partial deficiency in one of the eight enzymes involved in the heme biosynthesis. Our aim was to assess whether acute or cutaneous porphyria has been associated with excess risks of adverse pregnancy outcomes. A population-based cohort study was designed by record linkage between the Norwegian Porphyria Register, covering 70% of all known porphyria patients in Norway, and the Medical Birth Registry of Norway, based on all births in Norway during 1967-2006. The risks of the adverse pregnancy outcomes preeclampsia, delivery by caesarean section, low birth weight, premature delivery, small for gestational age (SGA), perinatal death, and congenital malformations were compared between porphyric mothers and the rest of the population. The 200 mothers with porphyria had 398 singletons during the study period, whereas the 1,100,391 mothers without porphyria had 2,275,317 singletons. First-time mothers with active acute porphyria had an excess risk of perinatal death [adjusted odds ratio (OR) 4.9, 95% confidence interval (CI) 1.5-16.0], as did mothers with the hereditable form of porphyria cutanea tarda (PCT) (3.0, 1.2-7.7). Sporadic PCT was associated with an excess risk of SGA [adjusted relative risk (RR) 2.0, 1.2-3.4], and for first-time mothers, low birth weight (adjusted OR 3.4, 1.2-10.0) and premature delivery (3.5, 1.2-10.5) in addition. The findings suggest women with porphyria should be monitored closely during pregnancy.

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.

Familial and sporadic porphyria cutanea tarda: clinical and biochemical features and risk factors in 152 patients

Porphyria cutanea tarda is the most frequent porphyria and occurs in both sporadic and familial forms. We conducted the current study in a series of 152 consecutive patients with porphyria cutanea tarda attending the Porphyria Unit of the Hospital Clinic of Barcelona, Spain, to update the clinical manifestations of the disease and to study the sex differences, the proportion of familial forms, and the role of different risk factors in this population. Patients were classified as familial and sporadic cases according to erythrocyte uroporphyrinogen-decarboxylase activity and uroporphyrinogen-decarboxylase genotyping. In our cohort, skin fragility and blisters on the hands were the most frequent clinical manifestations. Women more frequently had facial hypertrichosis (84.8%; p = 0.004), affected areas other than the hands and face (33.3%; p = 0.008), and pruritus (27.3%; p = 0.041) compared with men. Of our patients, 11.8% did not present the typical clinical onset of the disease, with facial hypertrichosis and hyperpigmentation the more frequent complaints in these cases. Analysis of risk factors showed a high prevalence of hepatitis C virus infection (65.8%) and alcohol abuse (59.9%), both being more frequent in men (p < 0.001). Hepatitis C virus infection was the only risk factor that showed differences between the sporadic and familial forms in the logistic regression model (odds ratio, 0.05; 95% confidence interval, 0.006-0.46). In conclusion, atypical forms of presentation of porphyria cutanea tarda should be considered in order to prevent delayed diagnosis. We note the sustained role of hepatitis C virus infection in the precipitation of sporadic porphyria cutanea tarda. Therefore, in countries with a high prevalence of hepatitis C virus infection, the absence of such infection in a patient with porphyria cutanea tarda may suggest a possible familial case.

Risk of HCC: genetic heterogeneity and complex genetics

Hepatocellular carcinoma (HCC) is a common form of cancer that arises from hepatocytes and whose risk may be affected by several known environmental factors, including hepatitis viruses, alcohol, cigarette smoking, and others. Rare monogenic syndromes, such as alpha1-antitrypsin deficiency, glycogen storage disease type I, hemochromatosis, acute intermittent and cutanea tarda porphyria, as well as hereditary tyrosinemia type I are associated with a high risk of HCC. Several common conditions or diseases inherited as polygenic traits e.g. autoimmune hepatitis, type 2 diabetes, a family history of HCC, hypothyroidism, and non-alcoholic steatohepatitis also show an increased risk of HCC compared to the general population. Overall, the genetic susceptibility to HCC is characterized by a genetic heterogeneity; a high individual risk of HCC may thus be caused by several unlinked single gene defects, whose carriers are rare in the general population, or by more common conditions inherited by complex genetics.