RESUMEN
Xeroderma pigmentosum is a rare autosomal recessive genodermatoses characterized by a deficiency in nucleotide excision repair. Erythropoietic protoporphyria is a rare inherited metabolic disease caused by the perturbation of heme. Xeroderma pigmentosum-erythropoietic protoporphyria is exceedingly rare. Hereby, we firstly report a young Chinese patient of xeroderma pigmentosum Group A with erythropoietic protoporphyria carrying an XPA Met214AsnfsTer7 frameshift mutation and a homozygous splicing mutation, c.315-48T>C, in the proband's intron3 of FECH.
Asunto(s)
Ferroquelatasa , Protoporfiria Eritropoyética , Xerodermia Pigmentosa , Humanos , Protoporfiria Eritropoyética/genética , Protoporfiria Eritropoyética/complicaciones , Xerodermia Pigmentosa/genética , Xerodermia Pigmentosa/complicaciones , Ferroquelatasa/genética , Masculino , Proteína de la Xerodermia Pigmentosa del Grupo A/genética , Mutación , Pueblo Asiatico/genética , Femenino , China , Mutación del Sistema de Lectura , Pueblos del Este de AsiaRESUMEN
BACKGROUND: Erythropoietic protoporphyria is a rare disorder which represents an important health problem in children, causing painful photosensitivity. Little is known on the correlation between genetic profile and clinical manifestations. The standard of care for Erythropoietic protoporphyria is based on avoiding sun and using sun protections, but recent literature has suggested that cimetidine may have a role in improving sun sensitivity. Herein we report our case series describing the successful use of cimetidine and analyzing potential phenotype-genotype correlations. CASE PRESENTATION: This case series describes five patients presented to our Rheumatology Service complaining sun sensitivity. Blood exams and genetic analysis were consistent with the diagnosis of erythropoietic protoporphyria. Four of 5 patients received cimetidine in addition to standard therapies and the effect of treatment was evaluated by Erythropoietic Protoporphyria - Quality of Life questionnaire. CONCLUSIONS: Erythropoietic protoporphyria usually manifests in early childhood after a short sun exposure. Skin manifestations are the main reason for investigations, although sometimes they can be more subtle, leading to a significant diagnostic delay. Skin diseases in children can have profound effects on their family and social relationships. A treatment with cimetidine appears to be an excellent therapeutic option in children with Erythropoietic protoporphyria.
Asunto(s)
Trastornos por Fotosensibilidad , Protoporfiria Eritropoyética , Niño , Humanos , Preescolar , Protoporfiria Eritropoyética/diagnóstico , Protoporfiria Eritropoyética/terapia , Protoporfiria Eritropoyética/complicaciones , Ferroquelatasa/genética , Cimetidina , Calidad de Vida , Diagnóstico Tardío , Trastornos por Fotosensibilidad/etiologíaRESUMEN
Erythropoietic protoporphyria (EPP) is a very rare disease with an estimated prevalence of 1 in 200,000 individuals. Decreased ferrochelatase activity causes the accumulation of protoporphyrin in the body, and light exposure results in the generation of active oxygen, causing photosensitivity. Liver damage has the greatest influence on the prognosis, and liver transplantation is the only treatment option for patients with decompensated liver cirrhosis. We report a case of living-donor liver transplantation for decompensated liver cirrhosis associated with EPP. The patient was a 52-year-old male who led a normal life except for mild photosensitivity. When the patient was 37-year-old, hepatic dysfunction was noticed. At 48-year-old, high erythrocyte protoporphyrin levels, skin biopsy, and genetic tests resulted in a diagnosis of EPP. The patient underwent living- donor liver transplantation because of decompensated liver cirrhosis. In the operating room and intensive care unit, a special light-shielding film was applied to all light sources to block light with harmful wavelengths during treatment. Due to the need for special measures, a lecture on patients with EPP was given before surgery to deepen understanding among all medical professionals involved in the treatment. As a result, no adverse events occurred during the perioperative period, and the patient was discharged on the 46th post-operative day. Currently, the transplanted liver is functioning extremely well, and the patient is alive 3 years post-transplant. Herein, we describe a case of living donor liver transplantation for EPP with a brief literature review.
Asunto(s)
Hepatopatías , Trasplante de Hígado , Protoporfiria Eritropoyética , Masculino , Humanos , Persona de Mediana Edad , Adulto , Protoporfiria Eritropoyética/cirugía , Protoporfiria Eritropoyética/complicaciones , Protoporfiria Eritropoyética/genética , Trasplante de Hígado/efectos adversos , Donadores Vivos , Protoporfirinas , Ferroquelatasa/genética , Ferroquelatasa/metabolismo , Hepatopatías/complicaciones , Cirrosis Hepática/complicaciones , Cirrosis Hepática/cirugíaRESUMEN
BACKGROUND: Erythropoietic protoporphyria and X-linked protoporphyria are inborn errors of heme biosynthesis that cause elevated circulating levels of metal-free protoporphyrin and phototoxicity. Both disorders are characterized by excruciating phototoxic attacks after exposure to visible light. Dersimelagon is a new, orally administered, selective melanocortin 1 receptor agonist that increases levels of skin eumelanin. METHODS: We conducted a randomized, placebo-controlled, phase 2 trial to investigate the efficacy and safety of dersimelagon with respect to the time to onset and the severity of symptoms associated with sunlight exposure in patients with erythropoietic protoporphyria or X-linked protoporphyria. Patients 18 to 75 years of age were randomly assigned in a 1:1:1 ratio to receive placebo or dersimelagon at a dose of 100 or 300 mg once daily for 16 weeks. The primary end point was the change from baseline to week 16 in the time to the first prodromal symptom associated with sunlight exposure. Patients recorded daily sunlight exposure and symptom data in an electronic diary. Quality of life and safety were also assessed. RESULTS: Of the 102 patients (93 with erythropoietic protoporphyria and 9 with X-linked protoporphyria) who underwent randomization, 90% completed the treatment period. The mean daily time to the first prodromal symptom associated with sunlight exposure increased significantly with dersimelagon: the least-squares mean difference from placebo in the change from baseline to week 16 was 53.8 minutes in the 100-mg dersimelagon group (P = 0.008) and 62.5 minutes in the 300-mg dersimelagon group (P = 0.003). The results also suggest that quality of life improved in patients receiving dersimelagon as compared with placebo. The most common adverse events that occurred or worsened during treatment were nausea, freckles, headache, and skin hyperpigmentation. CONCLUSIONS: At both doses evaluated, dersimelagon significantly increased the duration of symptom-free sunlight exposure in patients with erythropoietic protoporphyria or X-linked protoporphyria. (Funded by Mitsubishi Tanabe Pharma; Endeavor ClinicalTrials.gov number, NCT03520036.).
Asunto(s)
Fármacos Dermatológicos , Trastornos por Fotosensibilidad , Protoporfiria Eritropoyética , Receptor de Melanocortina Tipo 1 , Humanos , Recién Nacido , Síntomas Prodrómicos , Protoporfiria Eritropoyética/complicaciones , Protoporfiria Eritropoyética/tratamiento farmacológico , Calidad de Vida , Piel/efectos de los fármacos , Luz/efectos adversos , Trastornos por Fotosensibilidad/etiología , Receptor de Melanocortina Tipo 1/agonistas , Administración Oral , Fármacos Dermatológicos/uso terapéuticoRESUMEN
Erythropoietic protoporphyria (EPP) is an inherited cutaneous porphyria caused by reduced expression of ferrochelatase, the enzyme that catalyzes the final step in heme biosynthesis. The resultant accumulation of protoporphyrin IX leads to severe, painful cutaneous photosensitivity, as well as potentially life-threatening liver disease in a small percentage of patients. X-linked protoporphyria (XLP) is clinically similar to EPP but results from increased activity of δ-aminolevulinic acid synthase 2, the first step in heme biosynthesis in the bone marrow, and also causes protoporphyrin accumulation. Although historically the management of EPP and XLP (collectively termed protoporphyria) centered around avoidance of sunlight, novel therapies have recently been approved or are in development, which will alter the therapeutic landscape for these conditions. We present 3 patient cases, highlighting key treatment considerations in patients with protoporphyria, including (1) approach to photosensitivity, (2) managing iron deficiency in protoporphyria, and (3) understanding hepatic failure in protoporphyria.
Asunto(s)
Hepatopatías , Trastornos por Fotosensibilidad , Protoporfiria Eritropoyética , Humanos , Protoporfiria Eritropoyética/terapia , Protoporfiria Eritropoyética/complicaciones , Ferroquelatasa/genética , Ferroquelatasa/metabolismo , Trastornos por Fotosensibilidad/etiología , Trastornos por Fotosensibilidad/terapia , Protoporfirinas , Hemo/metabolismoRESUMEN
Importance: Erythropoietic protoporphyria (EPP) is a rare and underdiagnosed genetic disease characterized by painful sensitivity to light. A better understanding and characterization of its light-induced cutaneous symptoms may aid in the identification of EPP in patients. Objectives: To describe the cutaneous symptoms of erythropoietic protoporphyria (EPP) and to determine if these symptoms are associated with the degree of light sensitivity. Design, Setting, and Participants: This was a cross-sectional study of adolescent and adult (≥15 years) patients with EPP across the US conducted by a single academic hospital via a remotely administered survey, measurements of light sensitivity by light dosimetry and by text message symptom assessments. Data analyses were conducted from November 2020 to April 2022. Exposures: Sunlight exposure. Main Outcomes and Measures: Self-reported symptoms and association with measured light sensitivity. Results: The study sample consisted of 35 patients with EPP (mean [SD] age, 39.1 (15.5) years; 21 [60%] female; 14 [40%] male; 35 [100%] White individuals). The patients' median [range] skin tone was 3.0 (1.0-8.0), based on self-reporting from 1 (lightest) to 12 (darkest). A total of 24 participants completed the light dosimeter measurements. Phototoxic reactions were characterized by pain (97%; 34 patients), burning (97%; 34), tingling (97%; 34), pruritus (83%; 29), allodynia (89%; 31), improvement of symptoms with cold (89%; 31), achiness (24%; 12), fatigue (46%; 16), mild swelling (83%; 29), severe swelling (63%; 22), erythema (51%; 18), petechiae (40%; 14), skin cracking (43%; 15), scabbing (46%; 16), scarring (66%; 23), and other chronic skin changes (40%; 14). Patients with EPP reported that their hands, feet, and face were most sensitive to light and that their shoulders and legs were least sensitive; 25.7% (9 patient) reported no chronic skin changes, and 5.7% (2 patients) reported never having had any visible symptoms. None of these findings varied with the degree of light sensitivity except that lower overall light sensitivity was associated with lower ranked sensitivity of the neck and arms. Conclusions and Relevance: The findings of this cross-sectional study suggest that patients with EPP have distinctive cutaneous symptoms that may aid in identification of this underdiagnosed disease. Characteristic EPP symptoms include light-induced cutaneous burning pain and occasional swelling, particularly over the hands, with a prodrome of pruritus and paresthesias. Minimal skin changes or the absence of visible skin changes during reactions to light, including lack of erythema, do not exclude an EPP diagnosis nor suggest low EPP disease burden.
Asunto(s)
Protoporfiria Eritropoyética , Adulto , Adolescente , Humanos , Masculino , Femenino , Protoporfiria Eritropoyética/complicaciones , Protoporfiria Eritropoyética/diagnóstico , Fotofobia , Estudios Transversales , Eritema , Prurito , ParestesiaRESUMEN
Erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP) are characterized by skin photosensitivity caused by accumulation of protoporphyrin IX. We aimed to review the clinical evidence of efficacy and safety of skin photosensitivity treatments in individuals with EPP or XLP. We systematically searched MEDLINE, Embase, the Cochrane Library, and ClinicalTrials.gov. A total of 40 studies with data on 18 treatment modalities were included. Comprehensive treatment safety data were obtained from the European Medicines Agency and the United States Food and Drug Administration. The studies used different outcome measures to evaluate the sensitivity without a generally accepted method to assess treatment effect on skin photosensitivity. Of the included studies, 13 were controlled trials. Gathered, the trials showed moderate positive effect of inorganic sunscreen application and subcutaneous implant of afamelanotide and no effect of organic sunscreen application, or oral treatment with beta-carotene, cysteine, N-acetylcysteine, vitamin C, or warfarin. Studies without control groups suggested treatment effect of foundation cream, dihydroxyacetone/lawsone cream, narrow-band ultraviolet B phototherapy, erythrocyte transfusion, extracorporeal erythrocyte photodynamic therapy, or oral treatment with zinc sulphate, terfenadine, cimetidine, or canthaxanthin, but the real effect is uncertain. Assessment of treatment effect on photosensitivity in patients with EPP or XLP carries a high risk of bias since experienced photosensitivity varies with both weather conditions, exposure pattern, and pigmentation. Controlled trials of promising treatment options are important although challenging in this small patient population.
Asunto(s)
Enfermedades Genéticas Ligadas al Cromosoma X , Trastornos por Fotosensibilidad , Protoporfiria Eritropoyética , Estados Unidos , Humanos , Protoporfiria Eritropoyética/tratamiento farmacológico , Protoporfiria Eritropoyética/complicaciones , Protectores Solares/uso terapéutico , Trastornos por Fotosensibilidad/etiología , Enfermedades Genéticas Ligadas al Cromosoma X/complicaciones , ProtoporfirinasRESUMEN
Erythropoietic protoporphyria (EPP) is an inherited metabolic disease caused by the deficiency in ferrochelatase (FECH) encoded by the FECH gene, and it is inherited in an autosomal recessive manner. EPP usually produces acute pain photosensitivity after exposure to sunlight in infancy or early childhood, and liver failure is the most serious associated complication. This article reported an adult female case of EPP complicated with thyrotoxicosis and liver dysfunction which is a rare condition. The patient's liver function improved after liver protection treatment, her thyroid function returned to normal, and her EPP symptoms improved significantly. Moreover, the c.286C>T gene mutation may be the pathogenic locus of EPP. For patients with abnormal liver function, the possibility of EPP should be considered after the common causes are excluded, and FECH gene detection should be done to confirm the diagnosis in time. When EPP is associated with thyrotoxicosis and liver dysfunction, priority may be given to hepatoprotective therapy.
Asunto(s)
Fallo Hepático , Protoporfiria Eritropoyética , Tirotoxicosis , Humanos , Preescolar , Femenino , Adulto , Protoporfiria Eritropoyética/complicaciones , Protoporfiria Eritropoyética/genética , Tirotoxicosis/complicaciones , MutaciónRESUMEN
Erythropoietic protoporphyria is a rare inherited metabolic disorder involving the heme biosynthesis pathway and leads to the accumulation of protoporphyrin in the erythrocytes or liver. Although peripheral neuropathy is known to develop occasionally in other types of porphyria, it rarely occurs in patients with erythropoietic protoporphyria. A 16-year-old boy was transferred to our hospital due to end-stage liver disease secondary to erythropoietic protoporphyria. Severe systemic peripheral neuropathy, similar to that presented in Guillain-Barré syndrome, developed; it was promptly managed with mechanical ventilation. Electrophysiological assessment of the presented neuropathy showed no responsiveness, indicating severe axonopathy. Six weeks after the transfer, liver transplant was performed.Postoperatively, hepatorenal syndromes improved immediately, and his erythrocyte protoporphyrin level decreased from 6291 to 174 µg/dL red blood cells.The patient started to move his limbs gradually and was weaned from mechanical ventilation 2 months after liver transplant. Eventually, he was discharged from hospital and was able to ambulate with assistance 10 months after liver transplant. To our knowledge, this is the first report detailing the clinical course in a patient with erythropoietic protoporphyria who recovered from severe systemic peripheral neuropathy after liver transplant.
Asunto(s)
Trasplante de Hígado , Enfermedades del Sistema Nervioso Periférico , Protoporfiria Eritropoyética , Humanos , Masculino , Adolescente , Protoporfiria Eritropoyética/complicaciones , Protoporfiria Eritropoyética/diagnóstico , Protoporfiria Eritropoyética/cirugía , Trasplante de Hígado/efectos adversos , Protoporfirinas/metabolismo , Resultado del Tratamiento , Enfermedades del Sistema Nervioso Periférico/diagnóstico , Enfermedades del Sistema Nervioso Periférico/etiología , Enfermedades del Sistema Nervioso Periférico/cirugíaRESUMEN
BACKGROUND: Erythropoietic protoporphyria (EPP) is a rare inherited disorder that causes the accumulation of protoporphyrin in the erythrocytes, skin, and liver. Severe protoporphyric hepatopathy results in liver failure, requiring both liver and bone marrow transplantation as a life-saving procedure and to correct the underlying enzymatic defect, respectively. CASE PRESENTATION: We report a 20-year-old man who underwent split liver transplantation using a right trisegment and caudate lobe graft for EPP-induced liver failure, but succumbed to a deadly combination of early relapse of EPP and subsequent, intractable, late-onset bile leakage from the cut surface of segment 4. EPP recurrence most likely created a high-risk situation for bile leakage from the non-communicating bile ducts of segment 4; therefore, this case shed light on the potential relationship between EPP recurrence and biliary complications. CONCLUSION: Physicians should recognize the potentially rapid and life-threatening progression of protoporphyric hepatopathy that leads to liver failure. For young patients with EPP, LT and sequential BMT should thoroughly be considered by a multidisciplinary team as soon as hepatic reserve deterioration becomes evident. Split liver transplantation should preferably be avoided and appropriate post-transplant management is critical before protoporphyrin depositions to the bile duct and hepatocyte causes irreversible damage to the liver graft.
Asunto(s)
Hepatopatías , Fallo Hepático , Trasplante de Hígado , Protoporfiria Eritropoyética , Humanos , Hígado/cirugía , Hepatopatías/complicaciones , Fallo Hepático/complicaciones , Fallo Hepático/cirugía , Trasplante de Hígado/métodos , Masculino , Protoporfiria Eritropoyética/complicaciones , Protoporfiria Eritropoyética/cirugía , Protoporfirinas , Recurrencia , Adulto JovenRESUMEN
Children with erythropoietic porphyria are generally under the care of paediatric dermatologists. When these children undergo major surgery, they are at risk of unusual complications due to their photosensitivity. Dermatologists may be consulted prior to surgery for advice. We describe a case of a child with erythropoietic porphyria undergoing open heart surgery, utilising an exchange transfusion alongside other strategies to minimise the risk of photosensitivity-induced haemolysis.
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Puente Cardiopulmonar , Recambio Total de Sangre , Protoporfiria Eritropoyética/complicaciones , Preescolar , Hemólisis , Humanos , Iluminación/efectos adversos , Masculino , Trastornos por Fotosensibilidad/etiologíaRESUMEN
BACKGROUND: In erythropoietic protoporphyria (EPP), which presents with severe painful phototoxicity, progressive deposition of protoporphyrins in hepatocytes and bile canaliculi may result in liver disease. Clinically EPP related liver disease ranges from mildly elevated liver enzymes to cirrhosis and acute cholestatic hepatic failure. The prevalence of liver disease in EPP, and factors predicting the risk of developing liver disease, have not been defined in a large series of unselected EPP patients. AIM: To determine the prevalence of liver disease in EPP-patients. METHODS: A single-center prospective unselected cohort study of 114 adult EPP patients, who underwent routine laboratory testing, abdominal ultrasonography and transient elastography to assess the presence of steatosis (controlled attenuation parameter,dB/m) and liver stiffness (kPa). RESULTS: 114 adult EPP patients were included. Elevated liver enzymes were found in 6.2% of the patients. Liver steatosis was detected in 29.0%, and significant fibrosis as assessed with liver stiffness measurements was present in 9.6% of patients. BMI positively predicted CAP-values (p = 0.026); and protoporphyrin IX levels (p = 0.043) positively predicted liver stiffness. CONCLUSIONS: This study demonstrates a prevalence of hepatic steatosis and fibrosis in adult EPP-patients comparable to that found in the general population. Protoporphyrin IX levels correlate with increased liver stiffness in EPP.
Asunto(s)
Hepatopatías , Protoporfiria Eritropoyética , Adulto , Estudios de Cohortes , Humanos , Hígado/diagnóstico por imagen , Estudios Prospectivos , Protoporfiria Eritropoyética/complicaciones , Protoporfiria Eritropoyética/epidemiologíaRESUMEN
CASE DESCRIPTION: A 6-month-old sexually intact male Clumber Spaniel was evaluated because of small stature, recurrent dermatitis of the head, and progressive pigmentary hepatopathy. CLINICAL FINDINGS: Clinicopathologic findings included nonanemic hypochromic microcytosis, hypocholesterolemia, persistently high serum liver enzyme activities, and anicteric hyperbilirubinemia. Histologic examination of liver biopsy specimens collected when the dog was 6 months and 2 years of age revealed expansion and bridging of portal tracts, occasional centrilobular parenchymal collapse, scattered lymphoplasmacytic infiltrates, and dark red to brown pigment within large aggregates of macrophages, engorged bile canaliculi, and hepatocytes. The pigment failed to stain for the presence of iron, copper, bile, and glycoprotein and, when examined with polarized microscopy, emitted a yellow to green birefringence with occasional Maltese cross configurations. Further analyses confirmed marked porphyrin accumulation in blood, urine, feces, and liver tissue; protoporphyrin accumulation in RBCs and liver tissue; and a signature porphyrin profile and fluorescence peak consistent with erythropoietic protoporphyria. Advanced protoporphyric hepatopathy was diagnosed. The chronic dermatopathy was presumed to reflect protoporphyric photosensitivity. TREATMENT AND OUTCOME: Management was focused on avoiding conditions known to induce heme synthesis and catabolism, administrating ursodeoxycholic acid and antioxidants S-adenosylmethionine and vitamin E, and avoiding sunlight exposure. At follow-up at 4 years of age, the dog was stable without evidence of jaundice but with probable persistent erythropoietic protoporphyria-related solar dermatopathy. CLINICAL RELEVANCE: Clinical and histologic features of congenital erythropoietic protoporphyria and resultant protoporphyric hepatopathy, the diagnosis, and the successful management of a dog with these conditions over 4 years were described. Veterinarians should consider porphyric syndromes when unusual pigmentary hepatopathies are encountered.
Asunto(s)
Enfermedades de los Perros , Hepatopatías , Protoporfiria Eritropoyética , Animales , Bilis , Enfermedades de los Perros/tratamiento farmacológico , Perros , Hígado , Hepatopatías/veterinaria , Masculino , Protoporfiria Eritropoyética/complicaciones , Protoporfiria Eritropoyética/veterinaria , Ácido UrsodesoxicólicoRESUMEN
BACKGROUND: Erythropoietic protoporphyria is a rare disease of heme biosynthesis resulting in excessive accumulation of protoporphyrin in various organs. The most typical symptom is photosensitivity caused by activated protoporphyrins (wavelength ~400 nm). Accumulated protoporphyrin in the liver also causes liver failure, and liver transplantation is the only life-saving treatment. Phototoxic injury to abdominal organs has been reported during liver transplantation. Thus, to avoid phototoxic injury during liver transplantation, it has previously been conducted with only shadowless lights and ceiling lights off in the operating theater. Here, we report a case of a safe and successful liver transplantation in a patient with erythropoietic protoporphyria where the operating theater lights were covered with polyimide film. CASE PRESENTATION: A 50-year-old man presented with hepatic failure owing to erythropoietic protoporphyria. Before liver transplantation, the shadowless lights and ceiling lights in the operating theater were covered entirely with polyimide film. This filter completely blocked the harmful wavelength of light (400-470 nm). Orthotopic liver transplantation was safely and successfully performed with adequate illumination and patient monitoring. The patient followed a normal postoperative course without phototoxic injuries or protoporphyrin re-accumulation. CONCLUSION: Covering not only shadowless lights but also all ceiling lights in the operating theater with the polyimide film allowed safe surgery, safe anesthesia, and safe monitoring of the patient who underwent liver transplantation for severe liver failure owing to erythropoietic protoporphyria.
Asunto(s)
Iluminación/métodos , Trasplante de Hígado/métodos , Quirófanos/métodos , Trastornos por Fotosensibilidad/prevención & control , Protoporfiria Eritropoyética/cirugía , Humanos , Fallo Hepático/etiología , Fallo Hepático/cirugía , Masculino , Persona de Mediana Edad , Trastornos por Fotosensibilidad/etiología , Protoporfiria Eritropoyética/complicacionesRESUMEN
Reduced ferrochelatase activity in erythropoietic protoporphyria (EPP) causes the accumulation of protoporphyrin IX (PPIX) leading to acute cutaneous photosensitivity and liver injury. Many EPP patients also have a mild hypochromic, microcytic anemia and iron deficiency. Iron deficiency can lead to decreased PPIX accumulation in another erythropoietic porphyria, congenital erythropoietic porphyria (CEP). Expression of the iron regulatory peptide hepcidin is negatively regulated by the serine protease TMPRSS6. Hepcidin induction by siRNA-mediated inhibition of TMPRSS6 expression reduces iron availability and induces iron deficiency. To interrogate the therapeutic potential of iron deficiency to modify EPP, we treated an ethylnitrosourea-induced mouse model of EPP, Fech m1Pas , with a GalNAc-conjugated Tmprss6 siRNA and PPIX levels, anemia and iron parameters were monitored. The GalNAc-RNAi therapeutic reduces Tmprss6 expression and induces mild iron deficiency in Fech m1Pas animals. However, decreases in erythrocyte PPIX levels and liver PPIX accumulation were not seen. These results indicate short-term induction of iron deficiency, at least in a murine model of EPP, does not lead to decreased PPIX production.