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The porphyrias are a group of disorders of heme biosynthesis, each characterized by an enzymatic defect in the heme biosynthetic pathway. Porphyria cutanea tarda (PCT) arises due to the inhibition of uroporphyrinogen decarboxylase (UROD) in the presence of hepatic iron and oxidative stress. Most patients with PCT have evidence of siderosis on liver biopsy, and the disease resolves with iron depletion. PCT manifests as skin fragility, blistering cutaneous lesions on sun-exposed areas, dark urine, and elevated plasma and urine porphyrins. Factors contributing to the development of PCT include alcohol use, hepatitis C virus infection, human immunodeficiency virus, estrogen use, UROD pathogenic variants, and hereditary hemochromatosis. Treatment includes therapeutic phlebotomy to decrease total body iron levels and low-dose hydroxychloroquine, which reduces hepatic porphyrin content. The following review explores the biology of PCT, the critical role of iron in disease pathogenesis, and our approach to the management of these patients., (Copyright © 2024 by The American Society of Hematology.)

Background: Despite its rarity, porphyria cutanea tarda (PCT) is globally recognized as the most common form of cutaneous porphyria. This study aims to review the underlying associations and treatment of PCT in Scotland., Methods: We retrospectively reviewed data on 27 patients diagnosed with PCT between 1987 and 2022 at the Scottish Cutaneous Porphyria Service., Results: Males slightly predominated (66.7%). The mean ± standard deviation (SD) age at diagnosis was 55.6 ± 12.5 years. Common associated factors were heavy alcohol intake (88.5%), genetic hemochromatosis (72%), smoking (45.5%), and hepatitis C virus infection (16%). Most had multiple associated factors (70.4%). Patients with genetic hemochromatosis with the C282Y genotype exhibited higher median transferrin saturation (69.5 vs. 35, P = 0.004) and ferritin levels (observed in males only) (1175 vs. 339; P = 0.014) than those with the H636D genotype. Most (52%) received combination therapy of venesection and antimalarials, followed by venesection monotherapy (32%) and antimalarial monotherapy (16%). Overall, 95.2% achieved biochemical improvement. Median time to improvement was 7, 5, and 9 months with venesection, antimalarial, and combined treatments, respectively (P = 0.173). Biochemical remission was achieved in 50% of patients. Remission occurred in 2/4 of patients with antimalarial monotherapy (median time 19 months) and 9/13 patients with combined treatment (median time 26 months). Biochemical relapse was found in three patients, all of whom received combination therapy., Conclusion: Excess alcohol intake and genetic hemochromatosis were the most common underlying associations with PCT in our Scottish cohort. Treatment for PCT should be individualized, and long-term follow-up is needed to monitor for disease relapse., (© 2024 the International Society of Dermatology.)

Porphyria cutanea tarda (PCT) is the commonest of the porphyrias (Semin Liver Dis 1998;18:67). It often occurs secondary to an underlying internal disorder, has significant impacts on liver health and longevity, and is a treatable disease. Thus, for the clinician, recognising the disease to make the correct diagnosis, identifying causative underlying diseases, and treating the porphyria and its complications, are crucial. Although reviews on the management of PCT have been written, there have recently been significant advances in the understanding of the factors predisposing to the disease, and of its wider health impacts. This review aims to help the clinician to diagnose and manage patients with PCT, with an emphasis on the impact of recent advances on clinical management., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

We present a case of a woman who presented with a photosensitive skin rash and blisters on her extremities which did not improve with steroids. These were associated with polyarthralgia and a deranged liver function test on her admission. Further workup revealed that the patient has an undiagnosed porphyria cutanea tarda (PCT) and hereditary haemochromatosis. The patient later underwent regular venesections which improved her condition. This case report not only illustrates the challenge in diagnosing PCT but also aims to highlight the association between PCT and hereditary haemochromatosis., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

Porphyria cutanea tarda is a rare disorder of heme metabolism due to deficiency of the enzyme uroporphyrinogen decarboxylase which is manifested as some typical dermatological features and hepatic dysfunction. The Hepatitis-C virus co-infection is common and it can be aggravated by other environmental factors. We report a case of porphyria cutanea tarda in a 37-year-old woman, who presented with recurrent skin blisters and has concomitant Hepatitis-C virus infection. She was taking oestrogen containing oral contraceptive pill for a long duration. The diagnosis of porphyria cutanea tarda was considered on the basis of clinical features and high level of urine porphyrin level. She was put on hydroxychloroquine and combination drugs for Hepatitis-C virus with significant improvement after 3 months of therapy.

History: In 2017, a 72-year-old woman was seen in the gastroenterology department with a 2-month history of mild and intermittent abdominal pain without other accompanying symptoms. Her medical history was unremarkable, except for a previous visit due to facial photodermatitis 3 years earlier. Diazepam for a sleeping disorder was the only chronic medication recorded. Results of physical examination, blood count, and basic metabolic panels including assessment of renal and liver function were normal; only the ferritin level was slightly elevated (265 ng/mL [595 pmol/L]; normal range, 10-120 ng/mL [22-269 pmol/L]). Abdominal US was performed, followed by multiphasic contrast-enhanced CT and liver MRI due to the findings of the first study. A diagnosis was not established in that moment, and acetaminophen was prescribed for pain relief. As the symptoms continued, laboratory tests and imaging studies were repeated 2 years later, with similar findings and no notable changes.

Porphyria cutanea tarda (PCT), the most common porphyria, is a rare photodermatosis characterized by fragile, hemorrhagic bullae and erosions with associated milia, hyperpigmentation, and hypertrichosis. SLE is a systemic connective tissue disease with approximately 80% of those affected manifesting cutaneous findings. These include malar and discoid rashes, photosensitivity, bullae, oral ulcerations, as well as a variety of other nonspecific findings. In this case, we illustrate a rare but established association between these two pathologic entities, and the resulting therapeutic challenge in treating a patient with both conditions. The concurrence of these two diseases poses therapeutic challenges with a paucity of evidence-based recommendations. Management with low dose weekly antimalarial therapy may be the appropriate middle ground in effectively treating the two co-morbid conditions especially in a patient with other underlying systemic conditions.

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., (Copyright © 2021 Elsevier España, S.L.U. All rights reserved.)

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., (© 2022. The Author(s).)

Competing Interests: The authors declare no conflict of interest.

Porphyria cutanea tarda is the most common type of porphyria. It is associated with a deficiency of uroporphyrinogen decarboxylase enzyme responsible for heme synthesis. Clinical manifestations are predominantly dermatological and very rarely present with ocular involvement. Although scleral thinning in the interpalpebral area is a well-documented entity, sight-threatening corneal involvement is rarely described. We, herein report a case of a 58-year-old man who presented with ocular surface dryness, photophobia and mild redness. Slit-lamp biomicroscopy revealed corneo-scleral thinning in both eyes. The diagnosis was confirmed with a urine porphyrin test, serum iron and serum ferritin levels. We started him on conservative management after which he was lost to follow-up. He presented again after 6 years with total corneal opacification and progressive loss of vision in the right eye., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Porphyria cutanea tarda (PCT) is the most common human porphyria, due to hepatic deficiency of uroporphyrinogen decarboxylase (UROD), which is acquired in the presence of iron overload and various susceptibility factors, such as alcohol abuse, smoking, hepatitis C virus (HCV) infection, HIV infection, iron overload with HFE gene mutations, use of estrogens, and UROD mutation. Patients with familial or type II PCT due to autosomal dominant UROD mutation also require other susceptibility factors, as the disease phenotype requires hepatic UROD deficiency to below 20% of normal. PCT clinically manifests with increased skin fragility and blistering skin lesions on sun exposed areas. The common age of presentation is 5th to 6th decade and occurs slightly more commonly in males. Although mild liver biochemical profile are common, advanced fibrosis and cirrhosis with hepatocellular carcinoma (HCC) can occasionally develop. Screening for HCC using ultrasound examination is recommended in PCT patients, especially with cirrhosis and advanced fibrosis. PCT is effectively and readily treatable with the use of either repeated phlebotomy or use of 100 mg hydroxychloroquine orally twice a week, and both the treatments are equally effective and safe. With the advent of new or direct antiviral agents for HCV infection, treatment of concomitant HCV has become safer and effective. Data are emerging on the benefit of these drugs as monotherapy for both PCT and HCV. After the achievement of remission of PCT, there remains a potential for relapse, especially when the susceptibility factors are not adequately controlled. Scanty data from retrospective and observational studies shows the relapse rate to be somewhat higher after remission with low-dose hydroxychloroquine as compared to phlebotomy induced remission. Future studies are needed on exploring mechanism of action of 4-aminoquinolines, understanding interaction of HCV and PCT, and relapse of PCT on long-term follow-up., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The location of the patient's lesions and multiple risk factors suggested that an uncommon disorder was at work.

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.

Porphyria cutanea tarda (PCT) is a condition of dysregulated heme synthesis that leads to accumulation of photosensitizing precursors with resultant fragility and blistering of the skin. It can be hereditary or acquired and has been known to be associated with hepatic C virus, alcohol, HIV, and estrogen. In this article, we report an unusual presentation of PCT associated with acute hemorrhagic pancreatitis in a 57-year-old man. He presented initially to a community hospital with acute onset of epigastric abdominal pain and new-onset ascites. Lipase was elevated. Diagnostic paracentesis was grossly bloody. He was then transferred to our institution for concern for acute hemorrhagic pancreatitis. On arrival, physical examination demonstrated vesicles and bullae with erythematous bases, in different stages of healing seen over the dorsal aspects of both hands with scaling, scarring, and hypopigmentation and hyperpigmentation of the skin. Laboratory evaluation and skin biopsy confirmed the diagnosis of PCT. Search for an underlying etiology failed to reveal typical predisposing factors. This report illustrates that acute hemorrhagic pancreatitis may be an underlying etiology for PCT.

Porphyrias are disorders caused by defects in the biosynthetic pathway of heme. Their manifestations can be divided into three distinct syndromes, each attributable to the accumulation of three distinct classes of molecules. The acute neurovisceral syndrome is caused by the accumulation of the neurotoxic porphyrin precursors, delta aminolevulinic acid, and porphobilinogen; the syndrome of immediate painful photosensitivity is caused by the lipid-soluble protoporphyrin IX and, the syndrome of delayed blistering photosensitivity, caused by the water-soluble porphyrins, uroporphyrin, and coproporphyrin. Porphyrias can manifest with one, or with a combination, of these syndromes, depending on whether one or more types of molecules are being accumulated. Iron plays a significant role in some of these conditions, as evidenced by improvements in both clinical manifestations and laboratory parameters, following iron depletion in porphyria cutanea tarda, or iron administration in some cases of X-linked erythropoietic protoporphyria. While the pathophysiology of a specific type of porphyrias, the protoporphyrias, appears to favor the administration of zinc, results so far have been conflicting, necessitating further studies in order to assess its potential benefit. The pathways involved in each disease, as well as insights into their pathobiological processes are presented, with an emphasis on the development of photosensitivity reactions.

The prevalence of diabetes mellitus is increased in patients with porphyria cutanea tarda. Different tests are available for diagnosing and screening for type II diabetes mellitus, however choosing the most suitable test is challenging. The pitfalls in the different tests along with the interfering comorbidities and treatments concerning patients with porphyria cutanea tarda complicate diagnosing these patients with diabetes mellitus. HbA1c, fasting glucose, or oral glucose tolerance are the current available tests, with HbA1c as first choice. Measuring HbA1c requires no fasting, however HbA1c can be false low if the patient is treated with phlebotomy or has liver cirrhosis or chronic hepatitis. Instead fasting glucose and oral glucose tolerance tests can be used if the patient is not acutely ill. If either of the tests give a result in the diagnostic range, the test should be repeated if the patient has no clinical symptoms of diabetes. Diagnosing diabetes mellitus is important for the purpose of early intervention, and this review provides the knowledge needed to diagnose this special patient group properly., (© 2018 The International Society of Dermatology.)

A 29-year-old woman with a 1.5 year history of photosensitive skin lesions on her hands presented with a malar rash, bullous lesions on her hands, and was diagnosed with subacute lupus erythematosus after serologies revealed a positive antinuclear antibody test (1:2560), and antibodies to Ro/SSA and dsDNA. Hydroxychloroquine (400 mg/day) was prescribed and the patient developed severe drug-induced liver injury. Biopsy of her bullous skin lesions was consistent with porphyria cutanea tarda, as were her serological and urinary exams. She was successfully treated with therapeutic phlebotomy. This case identifies porphyria cutanea tarda as an important differential diagnosis for the rheumatologist to consider when evaluating patients with bullous skin lesions. Hydroxychloroquine in lower doses is an effective treatment for porphyria cutanea tarda; at doses used to treat systemic lupus erythematosus and subacute cutaneous lupus, there is a potentially life-threatening complication of hepatotoxicity.

Background: Porphyria is a condition of cutaneous photosensitivity. It is unclear if radiotherapy (RT) is safe in patients with porphyria., Methods: We report a patient case with uncontrolled porphyria cutanea tarda treated with chemoradiation for p16-positive oropharyngeal cancer. Given the scarcity of data on this subject, we also conducted a literature review on the topic of radiation in patients with porphyria., Results: The patient in our study did not experience any unusual acute or late toxicity, despite receiving a high dose of cutaneous radiation. We also found the majority of the literature supports the safe use of therapeutic radiation in patients with porphyria., Conclusion: In this patient, and in the majority of the literature, radiation seems safe in patients with porphyria; however, there are few reports on the subject in the literature, therefore, caution is warranted., (© 2017 Wiley Periodicals, Inc.)

The porphyrias are a clinically and genetically heterogeneous group of relatively rare metabolic diseases that result from disorders in the biosynthesis of haeme. Porphyria cutanea tarda (PCT) is the most common type, accounting for 80-90% of all porphyrias, and is essentially an acquired disease, although PCT can also occur on a familial basis. We describe a 71-year-old female and a 62-year-old male patient, both of whom had several risk factors for developing PCT, ranging from iron overload due to a mutation in the hereditary haemochromatosis protein (HFE) gene, alcohol use, smoking, and exogenous oestrogen, to persistent hepatitis C infection. The clinical relevance of the several diagnostic modalities is important in PCT. Diagnostic evaluation is important in order to confirm the diagnosis, but also to evaluate the treatment response in the context of long-term follow-up in the prevention of late complications of PCT, i.e. hepatocellular carcinoma.

Patients with chronic graft versus host disease may exhibit a range of sclerotic features. Herein we present a patient with confirmed porphyria cutanea tarda who subsequently developed chronic graft versus host disease.

Porphyria cutanea tarda is prevalent in connective tissue disease, common in systemic lupus erythematosus. However, the co-existence of primary sjogren's syndrome and porphyria cutanea tarda is rare and poses diagnostic and therapeutic challenges. We report a case of porphyria cutanea tarda associated with primary sjogren's syndrome.

A 24-year-old man presented with pain, sticky discharge and loss of vision in the right eye. He has had typical skin manifestations of porphyria cutanea tarda (PCT) since 6 years and ophthalmological symptom for 6 weeks. On ophthalmological examination, visual acuity was light perception in the right eye and 6/12 in the left. There were bilateral, symmetrical temporal scleromalacia along with temporal corneal melting in both eyes and perforation in the right eye. Ultrasonography B-scan (USG B-scan) revealed a retinal detachment in the right eye. Artificial tear instillation was started every hour along with topical antibiotic coverage in both eyes. Additionally, ultraviolet protective sunglasses and hat for photo-protection was advised. The vision in the right eye improved to 5/60 along with subsidence of retinal detachment on repeat USG B-scan after 3 weeks.

Background: The clinical features of porphyria cutanea tarda (PCT) are usually distinctive and include blistering on sun-exposed areas, fragile skin, hypertrichosis and hyperpigmentation. Sclerodermatous changes are much less common, and may either reveal PCT or else appear later. We carried out a retrospective study of the files of six female patients presenting such lesions., Patients and Methods: Six women (age: 45 to 72 years) were referred for sclerodermatous lesions on sun-exposed areas of the upper body. In four patients, these lesions revealed PCT and in the remaining two patients they were indicative of previously treated but relapsing PCT. Four had sclerodermatous skin changes mimicking morphea of the neck and neckline, the top of the back and the face, while one presented more diffuse facial and cervical sclerosis. Associated alopecia was seen in three patients. The last patient presented isolated sclerodermiform alopecia. Associated malar hypertrichosis was seen in five cases and facial hyperpigmentation was noted in three cases. Four exhibited no blisters, cutaneous fragility, milia or photosensitivity. Histological findings were consistent with morphea or scleroderma in all cases. All patients presented abnormal liver tests: cirrhosis was present in four cases (primitive biliary cirrhosis, alcoholic cirrhosis and hepatitis C) and fatty liver in two cases. In four cases, there was excessive alcohol intake. Uroporphyrin levels were above the normal range in all cases. Local corticosteroid therapy associated with phlebotomy and/or low-dose hydroxychloroquine resulted in complete normalisation of porphyrin levels in four patients, with complete resolution of the cutaneous lesions in two patients and partial improvement in the other two., Discussion: Sclerodermatous changes are uncommon in PCT. They are not always late and secondary to the process of healing of blisters but can in fact constitute the first cutaneous symptom of the disease while revealing the underlying liver disease. Even in the absence of blisters, photosensitivity or cutaneous fragility, a diagnosis of PCT must be suspected in a setting of sclerodermatous changes distributed on the neck and face, or the neckline, or scarring alopecia, if associated with abnormal liver tests. Skin biopsy to confirm the diagnosis of scleroderma may delay the diagnosis, which is in fact based on porphyrin level. Normalization of the latter parameter under treatment allows regression of lesions., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

On review of past 10 years medical records, we could find four typical cases of porphyria with rare ocular manifestations. Cases 1, 2 and 4 have presented with features suggestive of acute scleritis. Based on clinical, biochemical and dermatological evaluation, all these three cases were diagnosed to have congenital erythropoietic porphyria. Case 1 was initially managed with scleral patch graft which on subsequent melt was managed with double layered amniotic membrane grafting along with conjunctival advancement and lateral paramedian tarsorrhaphy in both the eyes. Cases 2 and 4 were managed conservatively with artificial tear drops and general protective measures. Case 3 was presented with multiple failed grafts due to repeated ulceration and infection. Owing to multiple failed grafts, Boston keratoprosthesis was done and the patient is doing well with stable kertaoprosthesis at the last follow-up visit.

The porphyrias are a group of inherited disorders that result in defects in the enzymes of the haem biosynthetic pathway, causing photosensitive bullous skin eruptions or abdominal and neurological attacks. Enzymatic defects result in specific porphyrin excretory patterns that are diagnosed biochemically and can be confirmed by genetic testing. Defects in the coproporphyrinogen oxidase (CPOX) enzyme result in the autosomal dominant hereditary coproporphyria. Multiple mutations have been identified in the CPOX gene and incomplete penetrance is noted. Latent carriers without clinical evidence of disease are at risk of life-threatening attacks. Porphyria cutanea tarda may be inherited, but is more commonly acquired. Occasionally two forms of porphyria may co-exist. The importance of genetic testing is discussed., (© 2012 The Authors; Australasian Journal of Dermatology © 2012 The Australasian College of Dermatologists.)