Erythropoietic protoporphyria: altered phenotype after bone marrow transplantation for myelogenous leukemia in a patient heteroallelic for ferrochelatase gene mutations

Consecutive Liver and Bone Marrow Transplantation for Erythropoietic Protoporphyria: Case Report and Literature Review

BACKGROUND

Erythropoietic protoporphyria (EPP) is a rare inherited disease of heme biosynthesis resulting in the accumulation of protoporphyrin, characterized by liver failure in a minority of cases. Although liver transplant (LT) is the therapeutic strategy for advanced hepatic disease, it does not correct the primary defect, which leads to recurrence in liver graft. Thus, hematopoietic stem cell transplantation (HSCT) is an approach for treating EPP.

METHODS

We aim to describe the first sequential LT and HSCT for EPP performed in Latin America, besides reviewing the present-day literature.

RESULTS

The patient, a 13-year-old female with a history of photosensitivity, presented with symptoms of cholestatic and hepatopulmonary syndrome and was diagnosed with EPP. Liver biopsy demonstrated cirrhosis. She was submitted to a successful LT and showed improvement of respiratory symptoms. However, she had disease recurrence on the liver graft. She underwent a myeloablative HSCT using a matched unrelated donor, conditioning with BuCy (busulfan and cyclophosphamide), and GvHD (graft vs. host disease) prophylaxis with ATG (thymoglobulin), tacrolimus and methotrexate. Neutrophil engraftment occurred on D+18. She has presented mixed chimerism, but normalization of PP levels, being 300 days after HSCT, in good state of health and normal liver function.

CONCLUSIONS

Consecutive LT and HSCT for EPP is a procedure that has been described in 10 cases in the literature and, even though these patients are a highly diversified population, studies have shown favorable results. This concept of treatment should be considered in patients with established liver disease.

Hematopoietic stem cell transplant for erythropoietic porphyrias in pediatric patients

Cutaneous, hematopoietic, and hepatic manifestations of congenital erythropoietic porphyria (CEP) and erythropoietic protoporphyria (EPP) can be debilitating. We present our institution's experience with five patients with porphyria who underwent hematopoietic stem cell transplant (HSCT). Four patients with CEP, including three under age 2, received myeloablation. One patient with EPP, with prior liver transplant, received reduced intensity conditioning (RIC). Four patients are alive without porphyria symptomology and with full donor chimerism. HSCT corrects the defective heme pathway and should be considered early in patients with severe erythropoietic porphyrias to minimize end-organ damage. RIC regimens can minimize toxicity in patients with comorbidities.

Sequential paternal haploidentical donor liver and HSCT in EPP allow discontinuation of immunosuppression post-organ transplant

BACKGROUND

EPP is characterized by photosensitivity and by liver disease. When LT is performed in EPP, recurrence often occurs in the allograft due to ongoing protoporphyrin production in bone marrow. Therefore, curative treatment requires allogeneic HSCT after LT. Long-term immunosuppression could be spared by using the same donor for both transplants.

METHODS

A 2-year-old girl with EPP in liver failure underwent liver transplant from her father. Transfusion and apheresis therapy were used to lower protoporphyrin levels before and after liver transplant. Ten weeks after liver transplant, she underwent HSCT, using the same donor. Conditioning was with treosulfan, fludarabine, cyclophosphamide, and ATG. GVHD prophylaxis was with abatacept, methotrexate, MMF, and tacrolimus. We followed the patient's erythrocyte protoporphyrin and liver and skin health for 2 years after transplant.

RESULTS

After hematopoietic stem cell engraftment, a decline in protoporphyrin levels was observed, with clinical resolution of photosensitivity. Liver biopsies showed no evidence of EPP. Mild ACR occurred and responded to steroid pulse. Two years post-HSCT, the patient has been weaned off all immunosuppression and remains GVHD and liver rejection free.

CONCLUSIONS

Sequential liver and HSCT from the same haploidentical donor are feasible in EPP. This strategy can allow for discontinuation of immune suppression.

Protoporphyrin IX: the Good, the Bad, and the Ugly

Protoporphyrin IX (PPIX) is ubiquitously present in all living cells in small amounts as a precursor of heme. PPIX has some biologic functions of its own, and PPIX-based strategies have been used for cancer diagnosis and treatment (the good). PPIX serves as the substrate for ferrochelatase, the final enzyme in heme biosynthesis, and its homeostasis is tightly regulated during heme synthesis. Accumulation of PPIX in human porphyrias can cause skin photosensitivity, biliary stones, hepatobiliary damage, and even liver failure (the bad and the ugly). In this work, we review the mechanisms that are associated with the broad aspects of PPIX. Because PPIX is a hydrophobic molecule, its disposition is by hepatic rather than renal excretion. Large amounts of PPIX are toxic to the liver and can cause cholestatic liver injury. Application of PPIX in cancer diagnosis and treatment is based on its photodynamic effects.

Bone marrow transplant for X-linked protoporphyria with severe hepatic fibrosis

XLP is an erythroid porphyria that results in variable cutaneous photosensitivity due to accumulation of protoporphyrin. The genetic defect in XLP is mutation of the gene ALAS2, resulting in gain of function for the erythroid enzyme 5-aminolevulinate synthase 2. Previous reports have shown that protoporphyrin-induced liver disease may also occur in XLP, occasionally severe enough to warrant liver transplantation; however, transplantation may be followed by injury to the graft due to continued presence of the underlying metabolic disorder in the bone marrow. We present a case of XLP with severe liver disease successfully treated with HPCT to avoid liver transplantation. The case also demonstrates the feasibility of reduced intensity transplant to provide engraftment sufficient for correction of porphyria and tolerability of reduced intensity conditioning containing TLI in the face of severe liver injury.

Cutaneous porphyrias part II: treatment strategies

The porphyrias are diverse in pathophysiology, clinical presentation, severity, and prognosis, presenting a diagnostic and therapeutic challenge. Although not easily curable, the dermatological manifestations of these diseases, photosensitivity and associated cutaneous pathology, can be effectively prevented and managed. Sun avoidance is essential, and patient education regarding the irreversibility of photocutaneous damage is a necessary corollary. Beyond preventative measures, the care of fragile, vulnerable skin, and pain management, each of the porphyrias has a limited number of unique additional therapeutic options. Many of the treatments have been published only in small case series or anecdotal reports and do not have well-understood nor proven mechanisms of action. This article presents a comprehensive review of available therapeutic options and long-term management recommendations for the cutaneous porphyrias.

Annular elastolytic giant cell granuloma associated to late-onset X-linked dominant protoporphyria

X-linked dominant protoporphyria (XLDPP) is a genetic disorder that affects the synthesis of the heme group due to an increase in delta-aminolaevulinate synthase 2 (ALAS2) enzyme activity. Moreover, annular elastolytic giant-cell granuloma (AEGCG) is a rare reactive granulomatous dermatosis, usually associated with actinic damage. An 86-year-old man presented with edematous-erythematous lesions in photoexposed areas of the face and on the dorsum of both hands. Protoporphyrin levels in serum and feces were significantly elevated and a heterozygous frameshift mutation in the exon 11 of the ALAS2 gene: c.1706-1709del (p.Glu569GlyfsX24) was identified. Concomitantly, we observed an annular plaque with raised borders on the back of his right hand, clinically and histologically compatible with a diagnosis of AEGCG. Skin lesions disappeared only upon use of a physical sunscreen. We report two rare photodermatoses in an elderly patient and discuss the significance of dermal elastic fiber damage induced by the XLDPP as a main triggering factor of AEGCG.

Liver transplantation for acute-on-chronic liver failure from erythropoietic protoporphyria

Erythropoietic protoporphyria (EPP) is an inherited disorder of the heme metabolic pathway that is characterized by accumulation of protoporphyrin in the blood, erythrocytes, and tissues, and cutaneous manifestations of photosensitivity, all resulting from abnormalities in ferrochelatase (FECH) activity due to mutations in the FECH gene. Protoporphyrin is excreted by the liver, and excess protoporphyrin leads to cholelithiasis with obstructive episodes and chronic liver disease, finally progressing to liver cirrhosis. Patients with end-stage EPP-associated liver disease require liver transplantation. We describe here a 31-year-old male patient with EPP who experienced acute-on-chronic liver failure and underwent deceased-donor liver transplantation. Surgical and postoperative care included specific shielding from exposure to ultraviolet radiation to prevent photosensitivity-associated adverse effects. The patient recovered uneventfully and was doing well 24 months after transplantation. Future prevention and treatment of liver disease are discussed in detail.

In vivo binding of protoporphyrin IX to rat translocator protein imaged with positron emission tomography

In vitro experiments have shown that protoporphyrin IX (PPIX) binds to the translocator protein 18 kDa (TSPO), which transports cholesterol across the outer mitochondrial membrane. The purpose of this study was to examine whether binding of PPIX to TSPO can also be detected in vivo using positron emission tomography and [(11)C]PBR28, a radioligand that binds with high affinity and selectivity to TSPO. Rats were injected with a high dose of 5-aminolevulinic acid (ALA, 200 mg/kg i.v.), which is a precursor for PPIX. ALA-pretreatment significantly decreased the uptake of [(11)C]PBR28 in TSPO-rich organs such as heart, kidneys, lungs, parotid glands, and spleen by 57-80%. As a control experiment, injection of a receptor saturating does of PK 11195, which is selective for TSPO, produced a pattern of displacement similar to that after ALA but with greater magnitude (88-97%). This study provides the first evidence that PPIX binds in vivo to TSPO. Although PPIX at physiological concentrations would likely occupy an insignificant percentage of TSPOs, it does reach high-enough concentrations in porphyria to occupy and have pharmacological effects via this target.

[Inheritance in erythropoietic protoporphyria]

Erythropoietic protoporphyria (EPP) is an inherited disorder of heme biosynthesis that results from an accumulation of protoporphyrin IX in erythroid cells, plasma, skin and liver. EPP leads to acute photosensitivity and, in about 2% of patients, liver disease. EPP is a complex syndrome in which two genes are independently involved: FECH and ALAS2. More than 96% of unrelated EPP patients have ferrochelatase (FECH) deficiency (MIM 177000). Four percent of them present with autosomal recessive inheritance with two mutated FECH alleles. In dominant cases (95%) the inheritance of a common hypomorphic IVS3-48C FECH allele trans to a deleterious FECH mutation reduces FECH activity below a critical threshold. The frequency of the IVS3-48C allele differs widely from the Japanese (45%), to Black West Africans (<1%) populations. These differences in the frequency of this single common SNP account for the prevalence of overt EPP in different countries and for the absence of EPP in Black Africans. The phylogenic origin of the IVS3-48C haplotypes strongly suggests that the IVS3-48C allele arose from a single recent mutational event that occurred 60 Kyears ago. Acquired somatic mutation of FECH secondary to myeloid disease may also exceptionally cause EPP (<1%). Finally, about 4% of unrelated EPP patients have X-linked dominant protoporphyria (XLDPP) (MIM 300752) caused by gain-of-function mutations in the ALAS2 gene leading to an increased erythroid heme biosynthesis and subsequently an accumulation of protoporphyrin without any FECH deficiency.

Seasonal palmar keratoderma in erythropoietic protoporphyria indicates autosomal recessive inheritance

Erythropoietic protoporphyria (EPP) is an inherited disorder that results from partial deficiency of ferrochelatase (FECH). It is characterized clinically by acute photosensitivity and, in 2% of patients, liver disease. Inheritance is usually autosomal dominant with low penetrance but is recessive in about 4% of families. A cross-sectional study of 223 patients with EPP in the United Kingdom identified six individuals with palmar keratoderma. We now show that these and three additional patients, from six families, have an inherited subtype of EPP which is characterized by seasonal palmar keratoderma, relatively low erythrocyte protoporphyrin concentrations, and recessive inheritance. No patient had evidence of liver dysfunction; four patients had neurological abnormalities. Patients were hetero- or homoallelic for nine different FECH mutations; four of which were previously unreported. Prokaryotic expression predicted that FECH activities were 2.7-25% (mean 10.6%) of normal. Neither mutation type nor FECH activity provided an explanation for the unusual phenotype. Our findings show that palmar keratoderma is a clinical indicator of recessive EPP, identify a phenotype that occurs in 38% of reported families with recessive EPP that to our knowledge is previously unreported, and suggest that patients with this phenotype may carry a lower risk of liver disease than other patients with recessive EPP.

Liver transplantation for erythropoietic protoporphyria with hepatic failure: a case report

Erythropoietic protoporphyria (EPP) is a disorder of heme synthesis in which deficient ferrochelatase activity leads to excessive production and biliary excretion of protoporphyrin. The main clinical features--photosensitivity and hepatobiliary disease that may progress to liver failure--are caused by the toxicity of protoporphyrin. Orthotopic liver transplantation is an effective treatment of liver failure caused by EPP. In this report we have described an EPP Chinese man with end-stage liver disease. He was successfully transplanted. A 3-year follow-up study of protoporphyrin levels, liver tests, and liver biopsies showed no EPP recurrence after liver transplantation.

Gene Dosage Analysis Identifies Large Deletions of the FECH Gene in 10% of Families with Erythropoietic Protoporphyria

Erythropoietic protoporphyria (EPP) is an inherited cutaneous porphyria characterized by partial deficiency of ferrochelatase (FECH), accumulation of protoporphyrin IX in erythrocytes, skin, and liver, and acute photosensitivity. Genetic counseling in EPP requires identification of FECH mutations, but current sequencing-based procedures fail to detect mutations in about one in six families. We have used gene dosage analysis by quantitative PCR to identify large deletions of the FECH gene in 19 (58%) of 33 unrelated UK patients with EPP in whom mutations could not be detected by sequencing. Seven deletions were identified, six of which were previously unreported. Breakpoints were identified for six deletions (c.1-7887-IVS1+2425insTTCA; c.1-9629-IVS1+2437; IVS2-1987-IVS4+352del; c.768-IVS7+244del; IVS7+2784-IVS9+108del; IVS6+2350-TGA+95del). Five breakpoints were in intronic repeat sequences (AluSc, AluSq, AluSx, L1MC4). The remaining deletion (Del Ex3-4) is likely to be a large insertion-deletion. Combining quantitative PCR with routine sequencing increased the sensitivity of mutation detection in 189 unrelated UK patients with EPP from 83% (95% CI: 76-87%) to 93% (CI: 88-96%) (P=0.003). Our findings show that large deletions of the FECH gene are an important cause of EPP. Gene dosage analysis should be incorporated into routine procedures for mutation detection in EPP.

Liver transplantation for porphyria: who, when, and how?

Porphyrias are a heterogenous group of diseases that may result in disabling or life threatening neurovisceral symptoms and/or cutaneous photosensitivity. In acute intermittent porphyria, the clinical features, particularly neurological symptoms, may be life-threatening and disabling. Conventional treatment with human hemin, though effective in reducing symptoms, does not reverse neuropathy when structural nerve damage has occurred and may cause intense phlebitis. Liver transplantation (LT) may be considered as treatment for those with repeated life-threatening acute attacks resulting in poor quality of life, requirement of ventilatory support, and progressive loss of venous access due to hemin infusion. Patients with variegate porphyria (VP) present after puberty with neurovisceral symptoms and skin manifestations. LT resolved VP in the 1 patient reported in the literature. Aminolaevulinic acid dehydratase deficient porphyria is a rare autosomal recessive disorder and a child who presented with failure to thrive and required transfusions and parenteral nutrition did not improve with LT. In erythropoietic protoporphyria (EPP), there is excessive production of protoporphyrin in the bone marrow. Protoporphyrin is hepatotoxic and pigment loading of hepatocytes and bile canalicular sludging may result in progressive cholestasis and cirrhosis. LT is beneficial for such patients with end-stage liver disease. Perioperative management includes use of filters on operative lights to prevent skin burns and intestinal perforation. Other concerns include development of neuropathy, biliary complications, and recurrent liver disease. This review addresses the rationale, patient selection, evaluation, management issues, and technique of performing LT in various types of porphyria.

Curative bone marrow transplantation in erythropoietic protoporphyria after reversal of severe cholestasis

We report the case of a middle-age patient presenting with severe progressive protoporphyric cholestasis. To halt further progression of liver disease, medical treatment was given aimed at different mechanisms possibly causing cholestasis in erythropoietic protoporphyria. Within eighty days, liver biochemistry completely normalized and liver histology markedly improved. Bone marrow transplantation was performed to prevent relapse of cholestatic liver disease by correcting the main site of protoporphyrin overproduction. Thirty-three months after cholestatic presentation and ten months after bone marrow transplantation, liver and porphyrin biochemistry remains normal. The patient is in excellent condition and photosensitivity is absent. The theoretical role of each treatment used to successfully reverse cholestasis and the role of bone marrow transplantation in erythropoietic protoporphyria are discussed. Medical treatment can resolve hepatic abnormalities in protoporphyric cholestasis. Bone marrow transplantation achieves phenotypic reversal and may offer protection from future protoporphyric liver disease.

Sequential liver and bone marrow transplantation for treatment of erythropoietic protoporphyria

Erythropoietic protoporphyria is a disorder of heme synthesis in which deficient ferrochelatase activity leads to excess production and biliary excretion of protoporphyrin. The main clinical features, photosensitivity and hepatobiliary disease that may progress to liver failure, are caused by the toxicity of protoporphyrin. Liver transplantation has been used to treat liver failure in erythropoietic protoporphyria, but excess production of protoporphyrin by the bone marrow continues causing recurrence of liver disease in the majority of patients. This is the first report of successful sequential liver and bone marrow transplantation in a patient with liver failure as a result of erythropoietic protoporphyria. This combination corrected the severe phenotype, resolving the severe photosensitivity and halting erythropoietic protoporphyria associated liver graft injury. Splenectomy seemed to facilitate the successful bone marrow transplant.

Biosynthesis of heme in mammals

Most iron in mammalian systems is routed to mitochondria to serve as a substrate for ferrochelatase. Ferrochelatase inserts iron into protoporphyrin IX to form heme which is incorporated into hemoglobin and cytochromes, the dominant hemoproteins in mammals. Tissue-specific regulatory features characterize the heme biosynthetic pathway. In erythroid cells, regulation is mediated by erythroid-specific transcription factors and the availability of iron as Fe/S clusters. In non-erythroid cells the pathway is regulated by heme-mediated feedback inhibition. All of the enzymes in the heme biosynthetic pathway have been crystallized and the crystal structures have permitted detailed analyses of enzyme mechanisms. All of the genes encoding the heme biosynthetic enzymes have been cloned and mutations of these genes are responsible for a group of human disorders designated the porphyrias and for X-linked sideroblastic anemia. The biochemistry, structural biology and the mechanisms of tissue-specific regulation are presented in this review along with the key features of the porphyric disorders.

Contribution of a common single-nucleotide polymorphism to the genetic predisposition for erythropoietic protoporphyria

Erythropoietic protoporphyria (EPP) is an inherited disorder of heme biosynthesis that results from a partial deficiency of ferrochelatase (FECH). Recently, we have shown that the inheritance of the common hypomorphic IVS3-48C allele trans to a deleterious mutation reduces FECH activity to below a critical threshold and accounts for the photosensitivity seen in patients. Rare cases of autosomal recessive inheritance have been reported. We studied a cohort of 173 white French EPP families and a group of 360 unrelated healthy subjects from four ethnic groups. The prevalences of the recessive and dominant autosomal forms of EPP are 4% (95% confidence interval 1-8) and 95% (95% confidence interval 91-99), respectively. In 97.9% of dominant cases, an IVS3-48C allele is co-inherited with the deleterious mutation. The frequency of the IVS3-48C allele differs widely in the Japanese (43%), southeast Asian (31%), white French (11%), North African (2.7%), and black West African (<1%) populations. These differences can be related to the prevalence of EPP in these populations and could account for the absence of EPP in black subjects. The phylogenic origin of the IVS3-48C haplotypes strongly suggests that the IVS3-48C allele arose from a single recent mutational event. Estimation of the age of the IVS3-48C allele from haplotype data in white and Asian populations yields an estimated age three to four times younger in the Japanese than in the white population, and this difference may be attributable either to differing demographic histories or to positive selection for the IVS3-48C allele in the Asian population. Finally, by calculating the KA/KS ratio in humans and chimpanzees, we show that the FECH protein sequence is subject to strong negative pressure. Overall, EPP looks like a Mendelian disorder, in which the prevalence of overt disease depends mainly on the frequency of a single common single-nucleotide polymorphism resulting from a unique mutational event that occurred 60,000 years ago.

Liver transplantation for erythropoietic protoporphyria liver disease

In erythropoietic protoporphyria (EPP), there is excessive production of protoporphyrin, primarily in the bone marrow, resulting in increased biliary excretion of this heme precursor. Some patients will develop progressive liver disease that may ultimately require liver transplantation. However, excessive production of protoporphyrin by the bone marrow continues after transplantation, which may cause recurrent disease in the allograft. This study was performed to define post-transplant survival, the risk of recurrent disease, and specific management issues in patients transplanted for EPP liver disease. The patients studied consisted of twelve males and eight females, with an average age of 31 (range, 13-56) years at the time of transplantation. The estimated maximum MELD score prior to transplant was 21 (range, 15-29). Unique complications in the perioperative period were light induced tissue damage in four patients and neuropathy in six, requiring prolonged mechanical ventilation in four. Patient and graft survival rates were 85% at 1 year, 69% at 5 years, and 47% at 10 years. Recurrent EPP liver disease occurred in 11 of 17 patients (65%) who survived more than 2 months. Three patients were retransplanted at 1.8, 12.6, and 14.5 years after the initial transplant for recurrent EPP liver disease. In conclusion, the 5-year patient survival rate in patients transplanted for EPP liver disease is good, but the recurrence of EPP liver disease appears to diminish long term graft and patient survival.

Molecular studies of liver disease in erythropoietic protoporphyria

GOALS

The goal of this study was to define molecular determinants of liver disease in erythropoietic protoporphyria (EPP).

BACKGROUND

EPP is a genetic disorder in which deficient ferrochelatase activity causes excessive production of protoporphyrin, which is excreted in bile. Some patients develop liver disease that necessitates transplantation.

STUDY

Ferrochelatase gene analysis was done in 25 families with EPP to identify mutations and a polymorphism (IVS3-48c) that causes low gene expression. Expression of multiple hepatic genes was also examined by DNA microarray analysis in patients who had liver transplantation to identify genes with altered regulation.

RESULTS

Heterozygous ferrochelatase mutations were found in 43 individuals. In 94% of 31 symptomatic patients, 15 of whom had liver disease, the polymorphism was also present in the nonmutant allele. Explanted liver of patients who had transplantation showed significant change in expression of several genes involved in wound healing, organic anion transport, and oxidative stress.

CONCLUSIONS

Patients with EPP who develop liver disease usually have a mutation in one ferrochelatase allele that alters enzyme function, together with a polymorphism in the nonmutant allele that causes low gene expression. This results in significant increase in the hepatobiliary excretion of protoporphyrin, which can damage the liver through both cholestatic injury and oxidative stress.

Prevention of murine erythropoietic protoporphyria-associated skin photosensitivity and liver disease by dermal and hepatic ferrochelatase

Erythropoietic protoporphyria (EPP) is caused by a defect in ferrochelatase, leading to the accumulation of protoporphyrin predominantly in erythrocytes and hepatocytes, and resulting in skin photosensitivity upon leaching of blood protoporphyrin into the skin. Some patients also develop severe liver damage. Because the respective contributions of hepatic and erythrocytic protoporphyrin to the pathophysiology of EPP remain unclear, we investigated this question using the murine model of EPP. Transplantation of bone marrow from EPP mice to normal recipients resulted in elevated erythrocyte and plasma protoporphyrin levels. However, quantification of serum liver enzymes and bilirubin together with histopathologic examination of liver sections of mice up to 16 months post-transplantation showed no evidence of liver damage. Moreover, despite massive elevation of serum protoporphyrin, transplanted mice showed minimal evidence of skin photosensitivity. Photosensitivity could also be prevented locally by implanting skin grafts from normal mice onto the backs of EPP recipients. These data validate the hypothesis that the main source of toxic protoporphyrin originates from the erythrocytes. However, we unexpectedly observed that normal ferrochelatase activity in hepatic and dermal cells of wild-type mice is sufficient to prevent liver disease and significant skin photosensitivity. These findings may provide new strategies for the treatment of EPP.