The Cutaneous Porphyrias

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.

Dermatologic manifestations of hematologic disorders

Distinguishing key morphologic features and understanding the pathophysiology of common cutaneous manifestations of hematologic disorders is essential to ensure prompt and appropriate treatment. In fact, classic cutaneous signs may provide the first clue to the diagnosis of an underlying hematologic disease. Disorders of coagulation, vascular abnormalities, or cutaneous infiltration and deposition are responsible for the underlying pathophysiology of cutaneous manifestations in the majority of cases. Hematologists often feel ill-equipped in identifying morphologic changes in the skin. Thus, the purpose of this review is to provide a comprehensive overview of classic cutaneous manifestations and diagnostic considerations of the associated hematologic conditions. Though there is a specific focus on non-malignant disorders, those straddling the spectrum of malignancy are also discussed. In many disease states, the skin may serve as an important marker of an emerging hematologic disorder, so close collaboration and multidisciplinary input remain essential to provide optimal and timely care for these patients.

Observational pilot study of multi-wavelength wearable light dosimetry for erythropoietic protoporphyria

BACKGROUND

Erythropoietic protoporphyria (EPP) causes painful light sensitivity, limiting quality of life. Our objective was to develop and validate a wearable light exposure device and correlate measurements with light sensitivity in EPP to predict and prevent symptoms.

METHODS

A wearable light dosimeter was developed to capture light doses of UVA, blue, and red wavelengths. A prospective observational pilot study was performed in which five EPP patients wore two light dosimeters for 3 weeks, one as a watch, and one as a shirt clip.

RESULTS

Standard deviation (SD) increases from the mean in the daily blue light dose increased the odds ratio (OR) for symptom risk more than the self-reported outdoor time (OR 2.76 vs. 2.38) or other wavelengths, and a one SD increase from the mean in the daily blue light wristband device dose increased the OR for symptom risk more than the daily blue light shirt clip (OR 2.45 vs. 1.62). The area under the receiver operator curve for the blue light wristband dose was 0.78, suggesting 78% predictive accuracy.

CONCLUSION

These data demonstrate that wearable blue light dosimetry worn as a wristband is a promising method for measuring light exposure and predicting and preventing symptoms in EPP.

Dermatological Manifestations in Patients With Chronic Kidney Disease: A Review

Chronic kidney disease (CKD) is a progressive disease and has multiple clinical manifestations; when CKD reaches the end stage, at least one cutaneous manifestation appears due to some increased toxin levels or a constant proinflammatory state. Nonspecific manifestations include pruritus, xerosis, pigmentation disorders, acquired ichthyosis, purpuric spots, and nail disorders. Some specific manifestations are bullous dermatoses, acquired perforating dermatoses (APD), eruptive xanthoma, access site infections, calcifying disorders, and nephrogenic systemic fibrosis (NSF). All these cutaneous changes negatively impact patients; early recognition and diagnosis of these dermatoses will make a difference in their quality of treatment. Exploring a patient's skin is fundamental to suspect some diseases and increased toxin levels; pruritus occurs when uremic toxins are raised, and nail disorders are associated with hypoalbuminemia. This review provides the clinician with information on the clinical manifestations that occur in CKD, including epidemiology, pathophysiology, clinical manifestations, diagnosis, histopathology, treatment, and life impact of the dermatoses in CKD.

Illuminating Dersimelagon: A Novel Agent in the Treatment of Erythropoietic Protoporphyria and X-Linked Protoporphyria

Erythropoietic protoporphyria (EPP) is a genetic disorder stemming from reduced ferrochelatase expression, the final enzyme in the pathway of heme biosynthesis. A closely related condition, X-linked protoporphyria (XLP), bears similar clinical features although it arises from the heightened activity of δ-aminolevulinic acid synthase 2 (ALAS2), the first and normally rate-controlling enzyme in heme biosynthesis in developing red blood cells. Both of these abnormalities result in the buildup of protoporphyrin IX, leading to excruciating light sensitivity and, in a minority of cases, potentially fatal liver complications. Traditionally, managing EPP and XLP involved sun avoidance. However, the emergence of innovative therapies, such as dersimelagon, is reshaping the therapeutic landscape for these conditions. In this review, we summarize salient features of the properties of dersimelagon, shedding light on its potential role in advancing our understanding of treatment options for EPP and XLP.

Development and validation of diagnostic algorithms for the laboratory diagnosis of porphyrias

Porphyrias are rare metabolic disorders of the haem synthesis. They can present with acute neurovisceral attacks, cutaneous symptoms, or a combination of both. As they present with a wide variety of clinical symptoms, diagnosis is often delayed and correct interpretation of porphyria-related tests remains a challenge for many physicians. We developed and validated two algorithms for the laboratory diagnosis of porphyrias based on presenting symptoms. Based on a literature search and clinical/laboratory expertise, we developed algorithms for acute and cutaneous porphyrias. We validated these algorithms using all porphyria related laboratory test requests between January 1st 2000 and September 30th 2020 in UZ Leuven. In addition, we also evaluated our algorithm using samples from the European porphyria network (EPNET) external quality assessment scheme (2010-2021). Sensitivity of the algorithm for acute porphyria was 100.0% [74.9%-100.0%] (13 acute intermittent porphyria (AIP) and 1 variegate porphyria [VP]) with a specificity of 98.5% [91.0%-100.0%] (65 patients). Sensitivity of the algorithm for cutaneous porphyria was 100% [95.1%-100.0%] (7 VP, 59 porphyria cutanea tarda (PCT), 23 erythropoietic protoporphyria (EPP), 2 X-linked erythropoietic protoporphyria [XLEPP]) with a specificity of 93.9% [82.9%-98.5%]. There were no diagnostic samples of other types of porphyria. The algorithms correctly identified 18 of the 19 EPNET porphyria cases. One of the two hereditary coproporphyria cases was missed. The algorithms for acute and cutaneous porphyria showed high sensitivity and specificity and can be used to aid the clinician in correctly interpreting the laboratory findings of porphyria-related tests.

In vitro Assessment of Solar Filters for Erythropoietic Protoporphyria in the Action Spectrum of Protoporphyrin IX

Introduction: Subjects with erythropoietic protoporphyria rely on broad-spectrum sunscreens with high sun protection factor, which is not informative on efficacy in the absorption spectrum of protoporphyrin IX, spanning visible radiation and peaking around 408 nm. Photoactivation of protoporphyrin IX is responsible for painful skin photosensitivity in erythropoietic protoporphyria. The authors assessed the protective efficacy of six sunscreens in vitro in the absorption spectrum of protoporphyrin IX. Method: Transmittance measurements were performed in the 300-850 nm wavelengths on samples of six photoprotective products applied to polymethyl methacrylate plates. Porphyrin protection factor was calculated in the 300-700 nm region to provide a measurement for the efficacy of each product based on the action spectrum of protoporphyrin IX. Results: Product A showed the highest porphyrin protection factor among tested products with a median value of 4.22. Product A is a sunscreen containing organic filters, titanium dioxide and synthetic iron oxides, pigmentary grade active ingredients that absorb visible radiation. Other products showed inefficient protection in the visible, with transmittance between 75 and 95% at 500 nm. The low porphyrin protection factor of inorganic filter product B was attributed to particle micronization, as declared by the manufacturer. Conclusion: Adding porphyrin protection factor to sunscreen labeling could help patients with erythropoietic protoporphyria and other photosensitivity disorders identify products tailored on their specific needs. The development of sunscreens providing protection from visible radiation and excellent cosmetical tolerability could improve the lifestyle of patients with erythropoietic protoporphyria.

Sight-threatening progressive corneo-scleral involvement in porphyria cutanea tarda

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.

Photoprotection according to skin phototype and dermatoses: practical recommendations from an expert panel

Increasing evidence on the impact of the different wavelengths of sunlight on the skin demonstrates the need for tailored recommendations of sunscreen according to skin phototype and dermatoses, which is now possible due to advances in the filters and formulations of sunscreens. A selective literature search was performed by an international expert panel, focusing on the type of sunscreen to recommend for photoaging, skin cancers, photodermatoses, pigmentary disorders and skin inflammatory disorders. Protection against ultraviolet (UV)B is especially important for light skin as there is a high risk of sunburn, DNA damage and skin cancers. Darker skin may be naturally better protected against UVB but is more prone to hyperpigmentation induced by visible light (VL) and UVA. Protection against UVA, VL and infrared A can be helpful for all skin phototypes as they penetrate deeply and cause photoaging. Long‐wave UVA1 plays a critical role in pigmentation, photoaging, skin cancer, DNA damage and photodermatoses. Adapting the formulation and texture of the sunscreen to the type of skin and dermatoses is also essential. Practical recommendations on the type of sunscreen to prescribe are provided to support the clinician in daily practice.

Visible light. Part I: Properties and cutaneous effects of visible light

Approximately 50% of the sunlight reaching the Earth's surface is visible light (400-700 nm). Other sources of visible light include lasers, light-emitting diodes, and flash lamps. Photons from visible light are absorbed by photoreceptive chromophores (e.g., melanin, heme, and opsins), altering skin function by activating and imparting energy to chromophores. Additionally, visible light can penetrate the full thickness of the skin and induce pigmentation and erythema. Clinically, lasers and light devices are used to treat skin conditions by utilizing specific wavelengths and treatment parameters. Red and blue light from light-emitting diodes and intense pulsed light have been studied as antimicrobial and anti-inflammatory treatments for acne. Pulsed dye lasers are used to treat vascular lesions in adults and infants. Further research is necessary to determine the functional significance of visible light on skin health without confounding the influence of ultraviolet and infrared wavelengths.

An unusual bullous eruption: olanzapine induced pseudoporphyria

A 27-year-old man with a background of schizophrenia presented during the summer months with a 2-day history of a blistering eruption predominantly affecting his hands, forearms and face. He had not knowingly been exposed to any chemicals or toxins and was otherwise well. Clinical examination revealed multiple, large, tense blisters affecting the sun-exposed sites. Histology subsequently demonstrated subepidermal blisters with minimal inflammation and negative immunofluorescence. Porphyrin biochemistry including faecal, urinary and serum samples were unremarkable and thus a diagnosis of pseudoporphyria was reached. There were no obvious triggers, however, olanzapine (an atypical antipsychotic) had been commenced 2 months previously and was deemed to be the most likely cause. This is the first report of pseudoporphyria being associated with an atypical antipsychotic and highlights the importance of eliciting an accurate drug history by specifically enquiring about any recent medication changes that could account for the clinical presentation.

Congenital erythropoietic porphyria: Recent advances

Congenital erythropoietic porphyria (CEP) is a rare autosomal recessive disorder characterized by photosensitivity and by hematologic abnormalities in affected individuals. CEP is caused by mutations in the uroporphyrinogen synthase (UROS) gene. In three reported cases, CEP has been associated with a specific X-linked GATA1 mutation. Disease-causing mutations in either gene result in absent or markedly reduced UROS enzymatic activity. This in turn leads to the accumulation of the non-physiologic and photoreactive porphyrinogens, uroporphyrinogen I and coproporphyrinogen I, which damage erythrocytes and elicit a phototoxic reaction upon light exposure. The clinical spectrum of CEP depends on the level of residual UROS activity, which is determined by the underlying pathogenic loss-of-function UROS mutations. Disease severity ranges from non-immune hydrops fetalis in utero to late-onset disease with only mild cutaneous involvement. The clinical characteristics of CEP include exquisite photosensitivity to visible light resulting in bullous vesicular lesions which, when infected lead to progressive photomutilation of sun-exposed areas such as the face and hands. In addition, patients have erythrodontia (brownish discoloration of teeth) and can develop corneal scarring. Chronic transfusion-dependent hemolytic anemia is common and leads to bone marrow hyperplasia, which further increases porphyrin production. Management of CEP consists of strict avoidance of exposure to visible light with sun-protective clothing, sunglasses, and car and home window filters. Adequate care of ruptured vesicles and use of topical antibiotics is indicated to prevent superinfections and osteolysis. In patients with symptomatic hemolytic anemia, frequent erythrocyte cell transfusions may be necessary to suppress hematopoiesis and decrease marrow production of the phototoxic porphyrins. In severe transfection-dependent cases, bone marrow or hematopoietic stem cell transplantation has been performed, which is curative. Therapeutic approaches including gene therapy, proteasome inhibition, and pharmacologic chaperones are under investigation.

Porphyrias: A clinically based approach

BACKGROUND

Porphyrias are a group of metabolic diseases, individually rare but with an important combined prevalence. Because of their pathological complexity and clinical heterogeneity, they present a challenging diagnosis. The present review aims to provide a clinically based approach to the recognition and treatment of these disorders.

METHODS

We carried out a search in PubMed, with the keyword "porphyria", for reviews published in English from 2010 until 2017.

RESULTS

The research yielded 196 papers, of which 64 were included in the final narrative review.

CONCLUSIONS

Porphyrias can be divided based on clinical presentation in acute neurovisceral, chronic cutaneous bullous, chronic cutaneous non-bullous and acute neurovisceral/chronic cutaneous bullous. Each individual porphyria presents a characteristic pattern of porphyrins in plasma, urine, stool and red blood cells. As such, diagnosis is easily obtained by following a simple diagnostic algorithm. Early recognition is key in managing these diseases. Neurovisceral porphyrias require acute support therapy and chronic eviction of precipitating factors. Cutaneous prophyrias, as photosensitivity disorders, rely on sunlight avoidance and, in some cases, specific therapeutic interventions. Given the rarity of these conditions, physician awareness is crucial.

[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.

Novel mutation of PPOX gene in a patient with abdominal pain and syndrome of inappropriate antidiuresis

PURPOSE

Acute porphyrias are metabolic disorders of heme biosynthesis characterized by acute life-threatening attacks. The diagnosis is often missed since clinical presentation is aspecific mimicking other medical and surgical conditions. Variegate porphyria (VP) is an autosomal dominant inherited disease with incomplete penetrance due to decreased activity of the Protoporphyrinogen Oxydase (PPOX) gene; most VP mutations are family specific. We report the case of a 40 year-old woman who presented many times to the emergency department complaining of unexplained abdominal pain and laboratory investigations showed repeatedly hyponatremia. Syndrome of inappropriate antidiuresis (SIAD) was confirmed and measurement of urine porphobilinogen and delta-aminolevulinic acid disclosed the diagnosis of acute porphyria. The genetic analysis of PPOX gene was performed.

METHODS

The entire coding sequence and exon/intron boundaries of PPOX gene were amplified in 5 different Polymerase Chain Reaction (PCR) fragments. In silico prediction of the pathogenicity of the mutation was determined by using different tools, Polyphen2, SNPs&GO, SNPs3D.

RESULTS

The genetic analysis of PPOX gene revealed a novel missense variant c.1376 G > A (p.Cys459Tyr) in heterozygous state. The same variant was later found in one of her cousins with skin lesions and other three younger asymptomatic relatives. We provided evidence that this novel mutation is likely to be pathogenetic.

CONCLUSIONS

Our case highlights the importance of considering VP in the differential diagnosis of SIAD and underlines the role of genetic screening in the management of such patients. The finding of a novel mutation of PPOX gene in our index case has allowed to recognize an affected family.

Porphyria: What Is It and Who Should Be Evaluated?

The porphyrias are a group of rare metabolic disorders, inherited or acquired, along the heme biosynthetic pathway, which could manifest with neurovisceral and/or cutaneous symptoms, depending on the defective enzyme. Neurovisceral porphyrias are characterized by acute attacks, in which excessive heme production is induced following exposure to a trigger. An acute attack usually presents with severe abdominal pain, vomiting, and tachycardia. Other symptoms which could appear include hypertension, hyponatremia, peripheral neuropathy, and mild mental symptoms. In severe attacks there could be severe symptoms including seizures and psychosis. If untreated, the attack might become very severe, affecting the peripheral, central, and autonomic nervous system, leading to paralysis, respiratory failure, hyponatremia, coma, and even death. From the biochemical point of view, acute attacks are involved with increased levels of precursors in the heme biosynthetic pathway, up to the deficient step. Of these precursors, aminolevulinic acid (ALA) is considered to be neurotoxic. Treatment is directed to reduce ALA production by reducing the activity of the enzyme aminolevulinate synthase (ALAS)-most effectively by heme therapy. Cutaneous symptoms are a consequence of elevated porphyrins in the blood stream. These porphyrins react to light; therefore sun-exposed areas are affected, producing fragile erosive skin lesions in porphyria cutanea tarda (PCT) or non-scarring stinging and burning symptoms in erythropoietic protoporphyria (EPP). Unlike the most common neurovisceral porphyria, acute intermittent porphyria (AIP), variegate porphyria (VP), and hereditary coproporphyria (HCP) can have cutaneous symptoms as well. Differentiating them from other cutaneous porphyrias is essential for accurate diagnosis, treatment, and patient recommendations.

Genetic ancestry of patients with porphyria cutanea tarda in a country with mixed races: a cross-sectional study (Rio de Janeiro - Brazil)

Porphyria cutanea tarda has a complex etiology with genetic factors not completely elucidated. The miscegenation of the Brazilian population has important implications in the predisposition to diseases. There are no studies concerning the genetic ancestry of patients with porphyria cutanea tarda from a mixed population. Thirty patients living in Rio de Janeiro with sporadic porphyria cutanea tarda were studied for the genetic ancestry through informative markers - INDELS. There was a significant predominance of European ancestry across the sample of patients with porphyria cutanea tarda (70.2%), and a small contribution of African and Amerindian ancestry, 20.1% and 10.9%, respectively.

Photosensitive disorders in HIV

Photosensitive disorders are common, affecting up to 5% of HIV-positive patients. HIV itself induces photosensitivity but photoaggravated drug reactions, porphyria cutanea tarda and nutritional disorders such as pellagra are also more common in patients with HIV. In South Africa, actinic lichenoid leukomelanoderma of HIV is a unique photosensitive disorder which is associated with advanced HIV. It is important to be able to recognise these conditions and withdraw photosensitising medications wherever possible.

Dermatologic Manifestations of Chronic Hepatitis C Infection

Chronic hepatitis C virus (HCV) infection is associated with various extrahepatic manifestations, including dermatologic involvement mostly caused by immune complexes. Mixed cryoglobulinemia has a strong relationship with HCV with 95% of these patients being infected with HCV. Lichen planus is a disease of the squamous epithelium and may affect any part of the skin, with 4% to 24% of patients with lichen planus reported to have chronic HCV infection. Porphyria cutanea tarda is the most common form of porphyria, and it is thought that HCV interferes with iron stores, which can promote porphyria cutanea tarda. Finally, necrolytic acral erythema is a rare, psoriasis-like disease closely associated with HCV.

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.

A Unique Neuropsychiatric Syndrome in Variant Hereditary Coproporphyria: Case Report and Review of the Literature

Hereditary coproporphyria (HCP) is the third most common of the acute porphyrias, after acute intermittent porphyria and variegate porphyria. It is caused by decreased activity of the sixth step in the heme biosynthetic pathway. Here we present a case of a woman with HCP who has experienced a wide variety of symptoms over several years. Most interesting among these is a unique neuropsychiatric syndrome marked by severe confusion, disorientation, and abnormal behavior. The literature is reviewed regarding the pathophysiology and management of neuropsychiatric manifestations of porphyria. As many other diagnoses are often considered before the diagnosis of porphyria is made, clinicians should keep in mind the highly variable neurological and psychiatric symptoms of porphyria.

Best practice guidelines on first-line laboratory testing for porphyria

The porphyrias are disorders of haem biosynthesis which present with acute neurovisceral attacks or disorders of sun-exposed skin. Acute attacks occur mainly in adults and comprise severe abdominal pain, nausea, vomiting, autonomic disturbance, central nervous system involvement and peripheral motor neuropathy. Cutaneous porphyrias can be acute or chronic presenting at various ages. Timely diagnosis depends on clinical suspicion leading to referral of appropriate samples for screening by reliable biochemical methods. All samples should be protected from light.

Investigation for an acute attack:

• Porphobilinogen (PBG) quantitation in a random urine sample collected during symptoms. Urine concentration must be assessed by measuring creatinine, and a repeat requested if urine creatinine <2 mmol/L.

• Urgent porphobilinogen testing should be available within 24 h of sample receipt at the local laboratory. Urine porphyrin excretion (TUP) should subsequently be measured on this urine.

• Urine porphobilinogen should be measured using a validated quantitative ion-exchange resin-based method or LC-MS.

• Increased urine porphobilinogen excretion requires confirmatory testing and clinical advice from the National Acute Porphyria Service.

• Identification of individual acute porphyrias requires analysis of urine, plasma and faecal porphyrins.

Investigation for cutaneous porphyria:

• An EDTA blood sample for plasma porphyrin fluorescence emission spectroscopy and random urine sample for TUP.

• Whole blood for porphyrin analysis is essential to identify protoporphyria.

• Faeces need only be collected, if first-line tests are positive or if clinical symptoms persist.

Investigation for latent porphyria or family history:

• Contact a specialist porphyria laboratory for advice. Clinical, family details are usually required.

[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.

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.

Hepatic porphyria: A narrative review

Porphyrias are a group of metabolic disorders, which result from a specific abnormality in one of the eight enzymes of the heme biosynthetic pathway. These have been subdivided based on the predominant site of enzyme defect into hepatic and erythropoietic types and based on clinical presentation into acute neurovisceral and cutaneous blistering porphyrias. This review focuses on hepatic porphyrias, which include acute intermittent porphyria (AIP), variegate porphyria (VP), hereditary coproporphyria (HCP), aminolevulinic acid dehydratase deficiency porphyria (ADP), and porphyria cutanea tarda (PCT). Of these, AIP and ADP are classified as acute porphyria, PCT as cutaneous, while VP and HCP present with both acute and cutaneous clinical manifestations. Porphobilinogen levels in a spot urine sample is the initial screening test for the diagnosis of acute hepatic porphyria, and plasma with spot urine porphyrin levels is the initial screening test to approach patients suspected of cutaneous porphyria. Specific biochemical porphyrin profile for each porphyria helps in determining the specific diagnosis. Pain relief and elimination of triggering agents are the initial steps in managing a patient presenting with an acute attack. Intravenous glucose administration terminates the mild episode of acute porphyria, with intravenous hemin needed for management of moderate to severe episodes. Liver transplantation is curative and may be needed for patients with a life-threatening acute porphyria attack or for patients with recurrent acute attacks refractory to prophylactic treatment. Of the cutaneous porphyrias, PCT is the most common and is frequently associated with a combination of multiple susceptibility factors such as alcohol use, smoking, hepatitis C virus infection, HIV infection, estrogen use, and mutations of the hemochromatosis gene. Regular phlebotomy schedule and low-dose hydroxychloroquine are effective and safe treatment options for management of PCT.

Acute Porphyria Presenting as Major Trauma: Case Report and Literature Review

BACKGROUND

Acute porphyria is historically known as "the little imitator" in reference to its reputation as a notoriously difficult diagnosis. Variegate porphyria is one of the four acute porphyrias, and can present with both blistering cutaneous lesions and acute neurovisceral attacks involving abdominal pain, neuropsychiatric features, neuropathy, hyponatremia, and a vast array of other nonspecific clinical features.

CASE REPORT

A 40-year-old man presented to the Emergency Department (ED) as a major trauma call, having been found in an "acutely confused state" surrounded by broken glass. Primary survey revealed: hypertension, tachycardia, abdominal pain, severe agitation, and confusion with an encephalopathy consistent with acute delirium, a Glasgow Coma Scale score of 13, and head-to-toe "burn-like" abrasions. Computed tomography was unremarkable, and blood tests demonstrated hyponatremia, acute kidney injury, and a neutrophilic leukocytosis. The next of kin eventually revealed a past medical history of variegate porphyria. The patient was experiencing an acute attack and received supportive management prior to transfer to intensive care, subsequently making a full recovery. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case highlights the importance of recognizing acute medical conditions in patients thought to be suffering from major trauma. Acute porphyria should be considered in any patient with abdominal pain in combination with neuropsychiatric features, motor neuropathy, or hyponatremia. Patients often present to the ED without any medical history, and accurate diagnosis can be essential in the acute setting to minimize morbidity and mortality. The label of the major trauma call must be taken with great caution, and a broad differential diagnosis must be maintained throughout a diligent and thorough primary survey.

Enhanced sensitivity of Neil1-/- mice to chronic UVB exposure

Oxidative stress and reactive oxygen species (ROS)-induced DNA base damage are thought to be central mediators of UV-induced carcinogenesis and skin aging. However, increased steady-state levels of ROS-induced DNA base damage have not been reported after chronic UV exposure. Accumulation of ROS-induced DNA base damage is governed by rates of lesion formation and repair. Repair is generally performed by Base Excision Repair (BER), which is initiated by DNA glycosylases, such as 8-oxoguanine glycosylase and Nei-Endonuclease VIII-Like 1 (NEIL1). In the current study, UV light (UVB) was used to elicit protracted low-level ROS challenge in wild-type (WT) and Neil1^-/- mouse skin. Relative to WT controls, Neil1^-/- mice showed an increased sensitivity to tissue destruction from the chronic UVB exposure, and corresponding enhanced chronic inflammatory responses as measured by cytokine message levels and profiling, as well as neutrophil infiltration. Additionally, levels of several ROS-induced DNA lesions were measured including 4,6-diamino-5-formamidopyrimidine (FapyGua), 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyAde), 8-hydroxyguanine (8-OH-Gua), 5,6-dihydroxyuracil (5,6-diOH-Ura) and thymine glycol (ThyGly). In WT mice, chronic UVB exposure led to increased steady-state levels of FapyGua, FapyAde, and ThyGly with no significant increases in 8-OH-Gua or 5,6-diOH-Ura. Interestingly, the lesions that accumulated were all substrates of NEIL1. Collectively, these data suggest that NEIL1-initiated repair of a subset of ROS-induced DNA base lesions may be insufficient to prevent the initiation of inflammatory pathways during chronic UV exposure in mouse skin.

The D519G Polymorphism of Glyceronephosphate O-Acyltransferase Is a Risk Factor for Familial Porphyria Cutanea Tarda

Both familial and sporadic porphyria cutanea tarda (PCT) are iron dependent diseases. Symptoms of PCT resolve when iron stores are depleted by phlebotomy, and a sequence variant of HFE (C282Y, c.843G>A, rs1800562) that enhances iron aborption by reducing hepcidin expression is a risk factor for PCT. Recently, a polymorphic variant (D519G, c.1556A>G, rs11558492) of glyceronephosphate O-acyltransferase (GNPAT) was shown to be enriched in male patients with type I hereditary hemochromatosis (HFE C282Y homozygotes) who presented with a high iron phenotype, suggesting that GNPAT D519G, like HFE C282Y, is a modifier of iron homeostasis that favors iron absorption. To challenge this hypothesis, we investigated the frequency of GNPAT D519G in patients with both familial and sporadic PCT. Patients were screened for GNPAT D519G and allelic variants of HFE (both C282Y and H63D). Nucleotide sequencing of uroporphyrinogen decarboxylase (URO-D) identified mutant alleles. Patients with low erythrocyte URO-D activity or a damaging URO-D variant were classified as familial PCT (fPCT) and those with wild-type URO-D were classified as sporadic PCT (sPCT). GNPAT D519G was significantly enriched in the fPCT patient population (p = 0.0014) but not in the sPCT population (p = 0.4477). Both HFE C282Y and H63D (c.187C>G, rs1799945) were enriched in both PCT patient populations (p<0.0001) but showed no greater association with fPCT than with sPCT. Conclusion: GNPAT D519G is a risk factor for fPCT, but not for sPCT.

How should hyperferritinaemia be investigated and managed?

Hyperferritinaemia is commonly found in clinical practice. In assessing the cause of hyperferritinaemia, it is important to identify if there is true iron overload or not as hyperferritinaemia may be seen in other conditions such as excess alcohol intake, inflammation and non-alcoholic fatty liver disease. Assessment of whether the serum ferritin level is elevated or not should take into account body mass index, gender and age. This review article provides an overview of the different causes of hyperferritinaemia, differentiating those due to iron overload from those not due to iron overload, and provides an algorithm for clinicians to use in clinical practice to carry out appropriate investigations and management.

[Porphyrias and haem related disorders]

The hereditary porphyrias comprise a group of eight metabolic disorders of the haem biosynthesis pathway characterised by acute neurovisceral symptoms, skin lesions or both. Each porphyria is caused by abnormal function of a separate enzymatic step resulting in a specific accumulation of haem precursors. Seven porphyrias are the consequence of a partial enzyme deficiency while a gain of function mechanism has been recently characterised in a novel porphyria. Acute porphyrias present with severe abdominal pain, nausea, constipation, confusion and seizure, which may be life threatening. Cutaneous porphyrias can be present with either acute painful photosensitivity or skin fragility and blisters. Rare recessive porphyrias usually manifest in early childhood with either severe chronic neurological symptoms or chronic haemolysis and severe cutaneous photosensitivity. Porphyrias are still underdiagnosed, but once they are suspected, and depending on the clinical presentation, a specific and simple front line test allows the diagnosis in all symptomatic patients. Diagnosis is essential to institute as soon as possible a specific treatment. Screening families to identify presymptomatic carriers is crucial to prevent chronic complications and overt disease by counselling on avoiding potential precipitants.

Clinical Approach to Diffuse Blisters

Some blistering eruptions are self-limited, but others are life threatening, and prompt diagnosis and management are critical. The clinical presentation of vesicles and bullae suggests a broad differential and this article (1) highlights some common diagnoses that may be encountered by primary care physicians and subspecialists; (2) provides a possible systematic diagnostic approach to such patients, including history, physical examination, and relevant work-up.

Porphyrias: A 2015 update

The hereditary porphyrias comprise a group of eight metabolic disorders of the heme biosynthesis pathway. Each porphyria is caused by abnormal function at a separate enzymatic step resulting in a specific accumulation of heme precursors. Porphyrias are classified as hepatic or erythropoietic, based on the organ system in which heme precursors (δ-aminolevulinic acid [ALA], porphobilinogen and porphyrins) are overproduced. Clinically, porphyrias are characterized by acute neurovisceral symptoms, skin lesions or both. However, most if not all the porphyrias impair hepatic or gastrointestinal function. Acute hepatic porphyrias present with severe abdominal pain, nausea, constipation, confusion and seizure, which may be life threatening, and patients are at risk of hepatocellular carcinoma without cirrhosis. Porphyria Cutanea presents with skin fragility and blisters, and patients are at risk of hepatocellular carcinoma with liver iron overload. Erythropoietic protoporphyria and X-linked protoporphyria present with acute painful photosensitivity, and patients are at risk of acute liver failure. Altogether, porphyrias are still underdiagnosed, but once they are suspected, early diagnosis based on measurement of biochemical metabolites that accumulate in the blood, urine, or feces is essential so specific treatment can be started as soon as possible and long-term liver complications are prevented. Screening families to identify presymptomatic carriers is also crucial to prevent overt disease and chronic hepatic complications.