[An overview of porphyrias]. / Porphyrien ­ eine Übersicht.

Porphyrias are predominantly genetic metabolic disorders caused by dysregulation of specific enzymes in porphyrin-heme biosynthesis. The enzymatic dysfunction leads to formation and excretion of intermediate metabolic products in the form of porphyrins and/or their precursors δ­aminolevulinic acid and porphobilinogen, which have cyto- and tissue-toxic properties. Clinically, porphyrias are extremely diverse, with symptoms ranging from skin changes on light-exposed areas of the body to potentially life-threatening neurovisceral attacks. Biochemical tests in urine, blood and stool are used for diagnosis, which can be supplemented by molecular genetic analyses. Treatment of the various forms of porphyria is complex and often requires close interdisciplinary cooperation between different medical specialties.

Further Characterization of the Neuroendocrine Phenotype Associated With the PPOX-Related Variegate Porphyria.

BACKGROUND: Variegate porphyria is caused by mutations in the PPOX gene; it usually presents in adolescents and adults as an autosomal dominant condition, with cutaneous features or acute peripheral and/or central nervous system crises. A rarer variant, homozygous variegate porphyria, presents in childhood with cutaneous manifestations as well as neurophenotypes. This study sought to further characterize the homozygous PPOX-related neuroendocrine phenotype. METHODS: This study is a retrospective review of the patients' charts, including their clinical evaluation and molecular genetics, neurodiagnostic, and neuroradiological investigations. RESULTS: We describe here three children from a consanguineous family who presented with nystagmus, developmental delay and ataxia, photosensitive skin manifestations, and adrenal insufficiency. Analysis of porphyrins in plasma, urine, and stool together with a genetic study of the PPOX gene confirmed the diagnosis. Interestingly, brain MRI showed severe hypomyelination, a finding rarely reported in variegate porphyria, together with adrenal insufficiency. CONCLUSION: We recommend analysis of porphyrins in unexplained hypomyelination disorders. Patients with variegate porphyria should be tested for adrenal insufficiency.

Key terms and definitions in acute porphyrias: Results of an international Delphi consensus led by the European porphyria network.

Acute porphyrias are a group of rare inherited disorders causing acute neurovisceral attacks. Many terms used frequently in the literature and clinical practice are ambiguous, which can lead to confusion in the way patients are managed, studied, and reported in clinical studies. Agreed definitions are a necessary first step in developing management guidelines and will facilitate communication of results of future clinical research. The Delphi method was used to generate consensus on key terms and definitions in acute porphyria. The process started with a brainstorming phase offered to all members of the European Porphyria Network followed by two Delphi rounds among international experts in the field of porphyria (the Acute Porphyria Expert Panel). A consensus of 75% or more was defined as the agreement threshold. A total of 63 respondents from 26 countries participated in the brainstorming phase, leading to the choice of nine terms and definitions. A total of 34 experts were invited to take part in the Delphi rounds. Seven of the initial nine terms and definitions which entered the first Delphi round achieved the threshold for agreement. Following a second Delphi round, all nine definitions achieved agreement. Agreement on the definitions for nine important terms describing acute porphyrias represents a significant step forward for the porphyria community. It will facilitate more accurate comparison of outcomes among porphyria centres and in clinical trials and provide a strong framework for developing evidence-based clinical guidelines.

Rare mutation of the PPOX gene in a patient with Porphyria Variegate: a case report in Peru / Mutación rara del gen PPOX en un paciente con Porfiria Variegata: reporte de un caso en Perú

ABSTRACT Introduction: Variegate porphyria (VP) is a rare disease, resulting from mutation of the protoporphyrinogen oxidase (PPOX) enzyme gene, and it is characterized by cutaneous manifestations and acute neuro-visceral symptoms. Case report: We describe the case of a 21-year-old woman from Peruvian highlands. The patient came to the emergency department for abdominal pain, quadriparesis and reddish urine. The patient also presented the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), motor neuropathy and respiratory failure. These clinical features were diagnosed as consequence of a porphyria crisis. The specific diagnosis was made with an elevated urinary porphobilinogen level (185.7 mg/24hours) and genetic analysis, which showed a rare pathogenic variant of the PPOX gene (nucleotide change: c.78C>A and protein change: p.Cys26*). The patient required intensive care until the administration of specific treatment with hemin. Conclusion: We report a case of VP with a pathogenic variant in the PPOX gene.

RESUMEN Introducción: La porfiria variegada (PV) es una enfermedad rara, resultante de la mutación del gen de la enzima protoporfirinógeno oxidasa (PPOX), se caracteriza por manifestaciones cutáneas y síntomas neuroviscerales agudos. Reporte de caso: Describimos el caso de una mujer de 21 años de la sierra peruana. La paciente acudió al servicio de urgencias por dolor abdominal, cuadriparesia y orina rojiza. La paciente también presentó el síndrome de secreción inapropiada de hormona antidiurética (SIADH), neuropatía motora e insuficiencia respiratoria. Estas características clínicas fueron diagnosticadas como consecuencia de una crisis de porfiria. El diagnóstico específico se realizó con un nivel elevado de porfobilinógeno en orina (185,7 mg/24horas) y el análisis genético, evidenció un rara variante patogénica del gen PPOX (cambio de nucleótido: c.78C>A y consecuentemente cambio de proteína: p.Cys26*). La paciente requirió cuidados intensivos hasta la administración de un tratamiento específico con hemina. Conclusion: Reportamos un caso de VP con una rara variante mutagénica en el gen PPOX.

Risk for incident comorbidities, nonhepatic cancer and mortality in acute hepatic porphyria: A matched cohort study in 1244 individuals.

The acute hepatic porphyrias (AHP) are associated with long-term complications such as primary liver cancer, hypertension, and chronic kidney disease. Data on other related comorbidities are scarce. In this register-based, matched cohort study, we assessed the risks of nonhepatic cancers, cardiovascular diseases, renal diseases, psychiatric disorders, and mortality in relation to porphyria type, sex, and biochemical disease activity. All patients in the Swedish porphyria register with a verified AHP diagnosis during 1987-2015 were included. The biochemical activity of acute intermittent porphyria was assessed using recorded maximal urinary porphobilinogen (U-PBG). Data on incident comorbidities and mortality were collected from national health registries. Cumulative incidences, rates, and hazards were compared to reference individuals from the general population, matched 1:10 by age, sex, and county. We identified 1244 patients with AHP with a median follow-up of 19 years. Health registries identified 149 AHP-subjects (12.0%) with nonhepatic cancer, similar to 1601 (13.0%) in the matched reference population (n = 12 362). Patients with AHP had a higher risk of kidney cancer (0.8% vs. 0.2%, p < 0.001), hypertension, and chronic kidney disease but no increase in risk for cardiovascular disease, except for cerebrovascular disease in patients with elevated U-PBG, (aHR = 1.40 [95% CI:1.06-1.85]). Mortality risk during follow-up was higher among patients with AHP (21% vs. 18%, p = 0.001), and associated with primary liver cancer, female sex, and biochemical activity. In conclusion, AHP is associated with an increased risk of kidney cancer, hypertension, chronic kidney disease, and mortality but not with cardiovascular disease or other nonhepatic cancers.

Case Report: Variegate porphyria disclosed by post-gastric bypass complications and causing predominant painful sensorimotor axonal peripheral neuropathy.

Background and aims: Porphyrias constitute a group of rare genetic diseases due to various, mostly autosomal dominant mutations, causing enzymatic deficiency in heme biosynthesis. As a result, neurotoxic porphyrin precursors and light-sensitive porphyrins accumulate, while dysfunction in their targets determines the disease symptoms. Variegate porphyria (VP), one of the acute hepatic porphyrias, is caused by a protoporphyrinogen oxidase (PPOX) mutation. During acute attacks, among other factors, triggered by drugs, stressors, or fasting, an increase in urinary and fecal porphobilinogen (PBG), aminolevulinic acid (ALA), and porphyrins occurs, damaging the autonomous, peripheral, or central nervous system. The disease remains often latent or displays minimal symptoms usually overlooked, exposing undiagnosed patients to potentially serious complications in the presence of the aforementioned triggers. Case report: This 46-year-old woman presented, some days after a bariatric surgery, with severe flaccid tetraparesis and neuropathic pain, initially misdiagnosed as a functional neurological disorder. The severe axonal sensorimotor polyneuropathy led to further investigations, disclosing high urinary porphobilinogen, ALA, and porphyrin levels due to a new PPOX mutation. Retrospectively, it appeared that the patient had had typical VP symptoms (abdominal pain, fragile skin, and dark urine episodes) for years prior to the surgery. Treated with carbohydrate load, neurorehabilitation, and analgesics, she slowly recovered to full mobility, with partial autonomy in her daily life activities, although fatigue and severe pain persisted, preventing her from returning to work. Conclusion: This case documents gastric bypass surgery as a trigger of severe VP invalidating neurological symptoms and illustrates how the delayed diagnosis and post-interventional complications could have been prevented by screening for porphyria cardinal symptoms prior to the intervention. Likewise, this cost-effective screening should be performed before any treatment influencing the diet, which would dramatically improve the porphyria diagnosis rate and outcome.

Therapy Follows Diagnosis: Old and New Approaches for the Treatment of Acute Porphyrias, What We Know and What We Should Know.

Heme, iron protoporphyrin IX, is one of life's most central molecules. Hence, availability of the enzymatic machinery necessary for its synthesis is crucial for every cell. Consequently, inborn errors of porphyrin metabolism that compromise normal synthesis, namely the family of porphyrias, undermine normal cellular metabolism given that heme has functions in catalytic centers, signal transduction and functional regulation and its synthesis is fully integrated into the center of intermediary metabolism. Very often, diagnosis of porphyrias is difficult and therefore delayed. Therapy can be as complicated. Over the last 50 years, several strategies have been developed: because of its integration with other parts of intermediary metabolism, the infusion of glucose (glucose effect) was one of the first attempts to counterbalance the dysregulation of porphyrin synthesis in porphyrias. Since heme synthesis is impaired, infusional replacement of heme was the next important therapeutic step. Recently, siRNA technology has been introduced in order to downregulate 5-ALA-synthase 1, which contributes to the patho-physiology of these diseases. Moreover, other novel therapies using enzyme protein replacement, mRNA techniques or proteostasis regulators are being developed.

Neurological Manifestations of Acute Porphyrias.

PURPOSE OF REVIEW: Porphyrias constitute a group of rare metabolic disorders that result in a deficiency of the heme biosynthetic pathway and lead to the accumulation of metabolic intermediaries. Patients with porphyria can experience recurrent neurovisceral attacks which are characterized by neuropathic abdominal pain and acute gastrointestinal symptoms, including nausea, vomiting, and constipation. Depending on the type of porphyria, patients can present with cutaneous manifestations, such as severe skin photosensitivity, chronic hemolysis, or evidence of neurologic dysfunction, including alterations in consciousness, neurovascular involvement, seizures, transient sensor-motor symptoms, polyneuropathy, and behavioral abnormalities. RECENT FINDINGS: More recently, cases of posterior reversible encephalopathy syndrome, cerebral vasoconstriction, and acute flaccid paralysis have also been described. While the exact pathogenic mechanisms linking the accumulation of abnormal heme biosynthetic intermediaries to neurologic manifestations have not been completely elucidated, it has been proposed that these manifestations are more common than previously thought and can result in permanent neurologic injury. This article reviews the basic principles of heme synthesis as well as the pathogenic mechanism of disease, presentation, and treatment of acute hepatic porphyrias with emphasis on those with neurologic manifestations.

Givosiran for the treatment of acute hepatic porphyria.

INTRODUCTION: Acute hepatic porphyrias (AHPs) are a family of rare inherited disorders characterized by enzyme dysfunctions in the hepatic pathway of heme biosynthesis. In AHPs, accumulation of the neurotoxic porphyrin precursors delta-aminolevulinic acid and porphobilinogen, caused by enhanced activity of hepatic aminolevulinate synthase 1 (ALAS1), is associated with acute, potentially life-threatening neurovisceral attacks. Symptoms during and between attacks dramatically reduce patients' quality of life (QoL). Givosiran is the first mRNA-targeted treatment for AHPs, silencing ALAS1 expression. AREAS COVERED: For givosiran, this review summarizes its chemistry, mechanism of action, pharmacokinetics, pharmacodynamics, safety, preclinical and clinical data in AHP, postmarketing surveillance, and regulatory status. A literature search of public and internal databases was performed, bibliographies of retrieved articles were manually searched to identify additional studies of relevance, and information was also provided by Alnylam Pharmaceuticals. EXPERT OPINION: Givosiran is a small interfering RNA (siRNA) therapeutic that reduces hepatic activity of ALAS1 and decreases accumulation of neurotoxic porphyrin precursors in patients with AHPs, ultimately reducing the number of acute attacks and improving symptoms and QoL between attacks. As AHPs are lifelong diseases, long-term safety data are needed for givosiran as an siRNA-based therapy.

Long-term follow-up of acute porphyria in female patients: Update of clinical outcome and life expectancy.

BACKGROUND: Acute hepatic porphyria includes four inherited disorders caused by partial deficiencies of enzymes related to the heme biosynthesis. Clinical manifestations include acute attacks, occurring mainly among female patients. This study describes the diversity of acute symptoms, changes in triggering factors and life expectancy among female patients during the past five decades. METHODS: 107 Finnish female patients were enrolled into a retrospective, longitudinal study during 2015. Clinical, biochemical and genetic data was obtained from the medical reports, registry data and a questionnaire designed for the study. Causes of death were studied in additional 32 female patients. RESULTS: Of the 43 patients with hospitalization, 33% had non-complicated, 35% prolonged and 28% severe attacks with no correlation with the disease-causing mutation. Of the deceased patients, 31% died of an acute attack during 1957-1979. Thereafter the incidence and severity of acute attacks have decreased substantially. 55% of the subjects reported acute symptoms (dysautonomia and mental symptoms) without hospitalization, 29% had porphyria symptoms >10 times, and 23% within the last year. Despite 22% of the female patients had died of primary liver cancer, the life expectancy increased more than 10 years during the follow-up, and did not differ from the normal population at present. CONCLUSIONS: The incidence of acute attacks requiring hospitalization has decreased, but more than half of the female patients reported acute symptoms affecting their well-being. Symptoms are currently triggered by hormonal changes and weight loss emphasizing the importance of early recognition and active management to avoid disease exacerbation. Death due to primary liver cancer is common and should be screened regularly.

A boy with blistering of sun-exposed skin and finger shortening: the first case of Variegate Porphyria with a novel mutation in protoporphyrinogen oxidase (PPOX) gene in Iran: a case report and literature review.

Variegate Porphyria (VP) is an inherited rare disorder that is caused by mutations in the protoporphyrinogen oxidase (PPOX) gene. This deficiency is associated with the accumulation of porphyrins and porphyrin precursors in the body, which, in turn, can potentially result in a variety of skin and neurological symptoms. Here, we reported a 7-year-old boy with homozygous VP and novel mutation on PPOX gene. He was admitted with three episodes of generalized tonic-clonic seizure in the last 6 months. He was presented with lesions, hyperpigmentation, fragility, and blistering of sun-exposed skin. The weakness of limbs and brachydactyly were observed. In the follow-up, he had aggressive behavior, learning disability and abdominal pain, particularly around the navel. Eventually, the whole exome sequencing (WES) result reported a novel homozygous pathogenic variant (c.1072G > A p.G358R) in PPOX gene which confirmed the VP. He had been advised to be away from the sun and use sunscreen regularly.

Molecular characterization of a novel His333Arg variant of human protoporphyrinogen oxidase IX.

Variegate porphyria is caused by mutations in the protoporphyrinogen oxidase IX (PPOX, EC 1.3.3.4) gene, resulting in reduced overall enzymatic activity of PPOX in human tissues. Recently, we have identified the His333Arg mutation in the PPOX protein (PPOX(H333R)) as a putative founder mutation in the Moroccan Jewish population. Herein we report the molecular characterization of PPOX(H333R) in vitro and in cells. Purified recombinant PPOX(H333R) did not show any appreciable enzymatic activity in vitro, corroborating the clinical findings. Biophysical experiments and molecular modeling revealed that PPOX(H333R) is not folded properly and fails to adopt its native functional three-dimensional conformation due to steric clashes in the vicinity of the active site of the enzyme. On the other hand, PPOX(H333R) subcellular distribution, as evaluated by live-cell confocal microscopy, is unimpaired suggesting that the functional three-dimensional fold is not required for efficient transport of the polypeptide chain into mitochondria. Overall, the data presented here provide molecular underpinnings of the pathogenicity of PPOX(H333R) and might serve as a blueprint for deciphering whether a given PPOX variant represents a disease-causing mutation.

mRNA-based therapy in a rabbit model of variegate porphyria offers new insights into the pathogenesis of acute attacks.

Variegate porphyria (VP) results from haploinsufficiency of protoporphyrinogen oxidase (PPOX), the seventh enzyme in the heme synthesis pathway. There is no VP model that recapitulates the clinical manifestations of acute attacks. Combined administrations of 2-allyl-2-isopropylacetamide and rifampicin in rabbits halved hepatic PPOX activity, resulting in increased accumulation of a potentially neurotoxic heme precursor, lipid peroxidation, inflammation, and hepatocyte cytoplasmic stress. Rabbits also showed hypertension, motor impairment, reduced activity of critical mitochondrial hemoprotein functions, and altered glucose homeostasis. Hemin treatment only resulted in a slight drop in heme precursor accumulation but further increased hepatic heme catabolism, inflammation, and cytoplasmic stress. Hemin replenishment did protect against hypertension, but it failed to restore action potentials in the sciatic nerve or glucose homeostasis. Systemic porphobilinogen deaminase (PBGD) mRNA administration increased hepatic PBGD activity, the third enzyme of the pathway, and rapidly normalized serum and urine porphyrin precursor levels. All features studied were improved, including those related to critical hemoprotein functions. In conclusion, the VP model recapitulates the biochemical characteristics and some clinical manifestations associated with severe acute attacks in humans. Systemic PBGD mRNA provided successful protection against the acute attack, indicating that PBGD, and not PPOX, was the critical enzyme for hepatic heme synthesis in VP rabbits.

Clinical, biochemical, and genetic characterization of acute hepatic porphyrias in a cohort of Argentine patients.

BACKGROUND: Acute Hepatic Porphyrias (AHPs) are characterized by an acute neuroabdominal syndrome including both neuropsychiatric symptoms and neurodegenerative changes. Two main hypotheses explain the pathogenesis of nervous system dysfunction: (a) the ROS generation by autooxidation of 5-aminolevulinic acid accumulated in liver and brain; (b) liver heme deficiency and in neural tissues that generate an oxidative status, a component of the neurodegenerative process. METHODS: We review results obtained from Acute Intermittent Porphyria (AIP) and Variegate Porphyria (VP) families studied at clinical, biochemical, and molecular level at the CIPYP in Argentina. The relationship between the porphyric attack and oxidative stress was also evaluated in AHP patients and controls, to identify a marker of neurological dysfunction. RESULTS: We studied 116 AIP families and 30 VP families, 609 and 132 individuals, respectively. Genotype/phenotype relation was studied. Oxidative stress parameters and plasma homocysteine levels were measured in 20 healthy volunteers, 22 AIP and 12 VP individuals. CONCLUSION: No significant difference in oxidative stress parameters and homocysteine levels between the analyzed groups were found.

Greater disease burden of variegate porphyria than hereditary coproporphyria: An Israeli nationwide study of neurocutaneous porphyrias.

Hereditary coproporphyria (HCP) and variegate porphyria (VP) are referred to as neurocutaneous porphyrias (NCP). Data concerning their systemic presentation are limited and no direct attempt of comparison of the two has ever been made. Our aim was to describe the type and frequency of systemic manifestations of NCPs in Israeli patients. A cross-sectional survey was conducted. The study population included all patients with NCP diagnosed at the Israeli National Service for Biochemical Diagnoses of Porphyrias (INSP) between 1988 and 2019. Of the 83 patients with NCP who were alive in 2019, 61 (73%) completed the survey, 40 with VP and 21 with HCP. Systemic symptoms were reported by 63% of the VP group and 62% of the HCP group (p = .96); corresponding rates of cutaneous symptoms were 58% and 5% (p < .001). We found no association between the occurrence of systemic and cutaneous symptoms. Among patients with systemic involvement, abdominal pain was the predominant systemic symptom, found in 64% of the VP group and 69% of the HCP group; Analysis of symptom frequency showed that in 68% of the VP group, systemic symptoms (either abdominal, musculoskeletal or neuropsychiatric) occurred on a daily/weekly basis, whereas the HCP group experienced less than one symptom per week (p < .001). This nationwide study depicts a significantly heavier disease burden in VP patients compared to HCP owing to its more frequent neurovisceral and cutaneous manifestations.

Comparative characterization of sun exposed and sun protected skin-derived mesenchymal-like stem cells in variegate porphyria and healthy individuals.

BACKGROUND AND PURPOSE: We hypothesized that upon sun exposure, a sub-population of primary skin-derived mesenchymal-like cells is deleteriously affected and thus contribute to the chronic inflammatory state in autosomal recessive variegate porphyria patients. The aim of this study was to isolate and characterize the mesenchymal-like stem cells from different areas of the skin in a porphyria patient (sun exposed, SE, and sun protected, SP) and to compare them with cells from a healthy individual. METHODS: The proliferation rate and the migration ability of SE and SP cells were evaluated in the presence of an antioxidant compound, N-acetylcysteine. A co-culture of SE-damaged cells with the conditioned medium from the enriched mesenchymal cell-like SP population was performed in order to regenerate the dermal injured tissue after sun exposure in patients. RESULTS: Results showed that the percentage of CD105+ cells varies between 3.9% in SP and 5% in SE of the healthy individual and between 3.6% and 1.4% in SP and SE in the porphyria patient, respectively. The osteogenic differentiation potential was lower in the porphyria patient when compared to the control. Furthermore, the expression of stem cell markers was more pronounced in SE than in SP cells of both control and porphyria. The use of N-acetyl cysteine did not show any beneficial effects on porphyria SE cells. Treatment with SP-conditioned medium slightly increased the expression of stem cell markers in SE of porphyria patient. CONCLUSION: In conclusion, the pool of mesenchymal stem-like SE cells is affected in variegate porphyria patient along with modification of their self-renewal and differentiation properties.

Novel PPOX exonic mutation inducing aberrant splicing in a patient with homozygous variegate porphyria.

INTRODUCTION: Variegate porphyria (VP; OMIM 176200) is one of the acute hepatic porphyrias, and it is characterized by the partial deficiency of protoporphyrinogen oxidase (PPOX). The unusual homozygous variant with mutations on both alleles of PPOX is distinguished with general heterozygous VP by several typical points such as severe defect in PPOX enzyme activity, early onset of photosensitivity before puberty, and skeletal deformity. MATERIAL AND METHOD: In this study, we describe a very rare case of autosomal recessive form of true homozygous VP found in a Chinese patient with consanguineous parents. Sanger sequencing of the PPOX gene showed a novel homozygous variant located at the first base of exon 8 of the gene, i.e., NM_000309.3c.808G > T. To investigate aberrant splicing induced by the mutant, wild-type exon 8 and mutant exon 8 were expressed in pET01 vector as minigene in cultured-cells and analyzed by RT-PCR. RESULTS: The wildtype PPOX showed an expected band in the gel electrophoresis after RT-PCR. The PPOX c.808G > T only showed a band similar to the band size of the vector only control. This result suggested c.808G > T mutant is an exonic mutation inducing aberrant splicing of pre-mRNA of the PPOX gene. CONCLUSION: This study showed a very rare case of homozygous VP with autosomal recessive homoallelic pattern. In comparison with previous cases of homozygous VP presenting brachydactyly, it is notable that our patient did not have any skeletal deformities.