Littérature scientifique sur le sujet « Non HFE Hemochromatosi »

Hereditary hemochromatosis (HH) is an iron metabolism disease clinically characterized by excessive iron deposition in parenchymal organs such as liver, heart, pancreas, and joints. It is caused by mutations in at least five different genes. HFE hemochromatosis is the most common type of hemochromatosis, while non-HFE related hemochromatosis are rare cases. Here, we describe six new patients of non-HFE related HH from five different families. Two families (Family 1 and 2) have novel nonsense mutations in the HFE2 gene have novel nonsense mutations (p.Arg63Ter and Asp36ThrfsTer96). Three families have mutations in the TFR2 gene, one case has one previously unreported mutation (Family A—p.Asp680Tyr) and two cases have known pathogenic mutations (Family B and D—p.Trp781Ter and p.Gln672Ter respectively). Clinical, biochemical, and genetic data are discussed in all these cases. These rare cases of non-HFE related hereditary hemochromatosis highlight the importance of an earlier molecular diagnosis in a specialized center to prevent serious clinical complications.

Abstract Genetic hemochromatosis (HH) is a common inherited disorder in populations of European origin in which different types of genetic hemochromatosis (type 1–4) have been characterized. Most hemochromatosis-type 1 patients are homozygotes or compound heterozygotes for two HFE mutations C282Y and H63D. Studies of several non-HFE iron overload families led to identification of mutations in hemojuvelin and hepcidin (juvenile form-HFE2A and B), transferrin receptor 2 (HFE3) and ferroportin (HFE4) as a cause of different forms of hemochromatosis. In the Far East, inherited hemochromatosis has rarely been reported and may have been misdiagnosed due to the high prevalence of secondary iron loading from hemoglobin disorders. This report describes, for the first time, non-HFE iron overload in patients from Southeast Asia. The affected Thai family presented with a distinctive clinical phenotype including macrocytosis and elevated transferrin saturation (>95%), increased non-transferrin bound iron (NTBI) as well as raised serum ferritin and marked hepatic hemochromatosis. Our patients tolerated therapeutic phlebotomy well. DNAs from peripheral blood leukocytes were firstly analyzed for three common HFE mutations (C282Y, H63D and IVS5+1 G→A). Subsequently, we screened all coding sequences, promoters and exon/intron boundaries of the HFE, HAMP, TfR2, HJV and SLC40A1 genes using denaturing high performance liquid chromatography (DHPLC). The entire coding region and splice sites of these genes were amplified and directly sequenced. We identified a novel mutation (C326Y) in ferroportin (SLC40A1, IREG-1, MTP-1), a membrane iron transport protein due to a G→A substitution at nucleotide 1281 in exon 7. This mutation was confirmed by restriction fragment length polymorphism (RFLP) analysis using Sfa NI. Six hundred Thai and two hundred Vietnamese chromosomes were analyzed for the C326Y mutation by RFLP analysis and it was not detected in any of the healthy controls studied. This result suggested that the G→A substitution is not a common polymorphism and is likely to be the causative mutation for the phenotype in this family. Previous reported mutations of ferroportin, including A77D and V162del, which lead to type IV hemochromatosis, were characterized by increased serum ferritin despite normal transferrin saturation, in contrast to our patients’ phenotype. These autosomal dominant mutants are postulated to lead to disease due to loss of iron exporting function. Preliminary in vivo assay using transient transfection of wild-type and ferroportin mutants in HeLa or 293T cells revealed, as expected, a loss of function and diminished surface membrane localisation in A77D and V162del mutants. Surprisingly, the C326Y mutant was indistinguishable from wt ferroportin in both iron status of the cell and protein localization suggesting different pathophysiology leading to iron overload in our patients.

Abstract Introduction Hereditary hemochromatosis (HH) is a genetic form of iron overload. In cases of excessive iron deposition, serious clinical manifestations may occur, such as liver damage, cardiomyopathy, diabetes, and arthritis. First described in 1996, the HFE gene leads to autosomal recessive HH with reduced penetrance. In other words, two mutations in the HFE gene need to be present in a patient in order to develop symptoms of HFE-related HH, but not all patients with two mutations are affected. In the last 15 years, 4 additional genes were discovered that cause HH: HAMP (hepcidin), HFE2 (hemojuvelin), SLC40A1 (ferroportin), and TFR2 (transferrin receptor 2). HAMP, HFE2 and TFR2 mutations are inherited in a recessive pattern, whereas SLC40A1 mutations are inherited in a dominant pattern. HAMP and HFE2 mutations cause a severe, early-onset form of HH. There is some evidence that sequence changes in HAMP, HFE2 and TFR2 may interact with homozygous HFE mutations, causing a more severe phenotype. Current HH testing guidelines only exist for the most common HFE mutations (C282Y and H63D), with no specific recommendations regarding full gene sequencing for any of the HH genes. Recent research suggests that sequential sequencing may be beneficial in patients who test negative for the most common HFE mutations, exhibit a more severe or early-onset phenotype compared to what is normally seen in HFE-related HH, and/or are of non-Caucasian ethnicity. Next Generation Sequencing (NGS) is a new high-throughput sequencing technology that allows testing of multiple genes concurrently and can detect rare and novel HH-causing mutations that are not typically assayed using targeted methods. However, sequencing can also identify sequence changes known as variants of uncertain significance (VUS) - changes that have not yet been characterized as disease-causing or benign. This abstract summarizes the results of clinical NGS for the five HH-related genes, and shows preliminary evidence as to its’ increased diagnostic yield for HH diagnosis. Methods Patients were referred for clinical full gene sequencing of HFE, HAMP, HFE2, SLC40A1, and/or TFR2 using Next Generation Sequencing (Illumina MiSeq). Results from patients with a clinical indication of iron overload or HH who were tested from 9/2013 - 7/2014 were reviewed. The diagnostic yield of sequencing for all five HH genes was determined. Patients who only had sequencing for a subset of the five genes were analyzed separately. Patients who had testing for a familial mutation were excluded from the review. Results In total, 56 patients underwent HH-related NGS. Thirty-five (62.5%) were males and 21 (37.5%) were females. Ages ranged from 3-77yrs (avg. 40.9yrs). Fifty-one percent were Caucasian, 9% Hispanic, 4% African American, 16% Asian, and 20% not specified. Forty-one patients were tested for all five genes. HH-causing mutations were found in 9 patients: 5 (12.2%) were c.187C>G (p.H63D) HFE homozygous, 1 (2.4%) was c.845G>A (p.C282Y) HFE homozygous, and 3 (7.3%) had mutations in non-HFE genes: SLC40A1 c.430A>T (p.N144Y) heterozygous, SLC40A1 c.533G>A (p.R178Q) heterozygous, and HFE2 c.959G>T (p.R178Q) homozygous. Nine patients (22%) were heterozygous carriers of an HFE mutation. One or more VUSes were found in 5 patients (12.2%). In 18 patients (43.9%), no pathogenic mutations or VUSes were found. There were 15 additional patients who only had sequencing of 1-3 of the available genes. Results for those patients consisted of 1 H63D HFE homozygote, 3 HFE heterozygotes (2 H63D and 1 C282Y) and 1 VUS. Conclusions The new sequencing technology of NGS makes it possible to test multiple genes at the same time. In this sample, sequencing of HFE, HAMP, HFE2, SLC40A1, and TFR2 genes resulted in an additional diagnostic yield compared to HFE C282Y and H63D testing alone. In patients who have a genetic explanation for their HH, management can be personalized based on genotype-phenotype correlation (e.g. N144Y SLC40A1 mutations may lead to reduced phlebotomy tolerance) and at-risk family members can be screened. In addition, all patients in this sample with non-HFE positive results were reportedly Caucasian, highlighting the benefit of sequencing regardless of ethnic background. This preliminary study is an important step toward gaining a better understanding of the genetics of HH. Ultimately, NGS data may make it possible to update current clinical guidelines for HH. Disclosures Rabideau: Invitae: Employment, Equity Ownership.

Key PointsThis comprehensive comparison of the genetic subtypes of hemochromatosis reveals more severe iron overload and disease in non-HFE forms. Arthropathy is more common in HFE-related hemochromatosis, suggesting that joint disease may not be associated with iron.

L’hémochromatose HFE est une maladie du métabolisme du fer liée au gène HFE dont la principale mutation est C282Y. L’objectif général de ce travail était d’étudier l’influence de facteurs génétiques et non génétiques sur l’expression phénotypique de patients atteints d’hémochromatose HFE. Cette étude prospective incluait les patients C282Y/C282Y etC282Y/H63D inclus en protocole de saignées entre janvier 2004 et décembre 2011 au centre de santé brestois de l’EFS-Bretagne. Dans un premier temps, nous avons étudié l’influence du génotype C282Y/H63D sur la survenue d’une surcharge en fer. Nous avons confirmé que le variant H63D doit être considéré comme un facteur de susceptibilité dont l’expression est liée à la présence de co-facteurs responsables d’une hyper ferritinémie. Ensuite, nous avons étudié le rôle des grossesses et de l’alimentation sur l’expression phénotypique du génotype C282Yhomozygote. Nous avons montré qu’il existe bien une différence d’expressivité clinique liée au sexe chez les patients C282Y/C282Y. Cependant, nos données n’ont pas confirmé l’effet protecteur typiquement attribué aux grossesses pour expliquer la plus lente accumulation de fer chez les femmes. Cette étude a également mis en évidence une association modérée entre la consommation d’aliments riches en fer et le degré de surcharge en fer des patients C282Yhomozygotes traités par phlébotomies. Ce travail contribue à mieux comprendre l’hétérogénéité phénotypique observée dans l’hémochromatose HFE. La finalité est de pouvoir repérer précocement les sujets les plus à risque de développer les surcharges en fer les plus sévères et par conséquent des complications cliniques
HFE hemochromatosis is a disorder of iron metabolism related to the HFE gene whose mainmutation is C282Y. The overall aim of this study was to investigate the influence of genetic and non genetic factors on phenotypic expression of patients with HFE hemochromatosis. This prospective study included the C282Y/C282Y and C282Y/H63D patients enrolled in a phlebotomy program between 2004 and 2011 in a blood centre of western Brittany (Brest, France). First, weassessed the weight of the C282Y/H63D genotype in the occurrence of iron overload. We confirmed that H63D is a discrete genetic susceptibility factor whose expression is most visible in association with other co-factors responsible for hyper ferritinemia. Then we investigated the effect of pregnancies and iron-rich diet on phenotypic expressivity of the C282Y/C282Y genotype. We have shown that there is a difference in clinical expression related to gender in C282Y/C282Ypatients. However our findings did not confirm that pregnancies protect against iron accumulationin women. This study established a moderate link between dietary iron intake and the degree of iron overload in HFE hemochromatosis patients who come to medical attention. This work contributes to a better understanding of the phenotypic heterogeneity observed in HFE hemochromatosis. The purpose is to identify precociously subjects the most at risk of developing iron overload and therefore clinical complications

L’Emocromatosi Ereditaria (EE) è una delle malattie genetiche più comuni nella popolazione caucasica con un’incidenza di 5 malati su 1000 individui (0.5 %). La diagnosi precoce della malattia è di fondamentale importanza per il trattamento dei pazienti ed è stata notevolmente migliorata con la scoperta del gene HFE nel 1996 e con il successivo sviluppo di un semplice test genetico-molecolare delle mutazioni C282Y e H63D sul gene HFE. La maggior parte degli individui con EE sono omozigoti per la mutazione C282Y o eterozigoti composti C282Y/H63D, i due genotipi considerati diagnostici per l’Emocromatosi classica HFE-correlata. Tuttavia, essendo l’EEuna malattia geneticamente eterogenea, circa il 30% dei pazienti presenta forme di Emocromatosi non correlate al gene HFE e mutazioni in almeno altri quattro geni coinvolti nella modulazione dell’asse epcidina-ferroportina, i.e. HAMP, HJV, TFR2, SLC40A1, sono considerate responsabili dell’espressione della malattia in questi pazienti.Le mutazioni a carico di questi altri quattro geni sono considerate private, ovvero limitate a pochi individui, necessitando, per un’appropriata diagnosi molecolare, di tecniche di sequenziamento disponibili solo presso centri specializzati. Negli ultimi anni, lo sviluppo di metodiche di sequenziamento di “ultima generazione” sta semplificando tale approccio a costi progressivamente inferiori.Il presente progetto ha lo scopo di mettere a punto un test rapido e accurato per la diagnosi molecolare di EE “atipica”, che possa supportare i clinici che si confrontano con tali casi, colmando in tal modo un gap della pratica clinica attuale. In questo lavoro di tesi abbiamo studiato 47 pazienti con evidenti segni biochimici di sovraccarico di ferro (IO) e negativi per il test genetico di primo livello suggerendo la presenza di EE non correlata al gene HFE. I cinque geni dell’Emocromatosi sono stati catturati mediante la tecnologia Halo-Plex™ e successivamente sequenziati usando una piattaforma di ultima generazione (Illumina HiSeq 1000). Le reads sono state allineate contro il genoma umano di riferimento HG19 e successivamente analizzate mediante il software GoldenHelix™ per annotare tutte le varianti eventualmente coinvolte nella malattia. Nei pazienti con IO sono state trovate un numero consistente di nuove varianti non sinonime (usando strumenti bioinformatici che si basano su database disponibili incluso il progetto 1000 Genomes). Molte delle varianti trovate sono relativamente frequenti e presenti anche nei soggetti controllo, e quindi sono state considerate non patogenetiche. Dall’altro lato, alcune varianti rare (limitate a un singolo individuo o a un numero molto limitato di soggetti) sui geni SCL40A1, TFR2 e HFE sono state trovate in maniera esclusiva nei pazienti e otto di queste varianti non sono mai state riportate nei databasesdbSNPs, 1000, Genomes, OMIM e ESP. Queste nuove varianti rare sono in grado di spiegare la correlazione fenotipo/genotipo nei pazienti negativi per il test genetico di primo livello e quindi sono state considerate potenzialmente patogenetiche. La combinazione della tecnologia Halo-Plex™ con la piattaforma di sequenziamento di ultima generazione e con il software GoldenHelix™ sembra rappresentare un approccio adatto per una migliore caratterizzazione molecolare dei pazienti con EE “atipica” e per l’implementazione di un test genetico di secondo livello nei centri di riferimento specializzati. Tuttavia stabilire la rilevanza clinica delle nuove varianti genetiche ottenute mediante un approccio di questo tipo in una malattia prevalentemente autosomica recessiva come EE rimane un compito difficile che richiede ulteriori studi funzionali e collaborazioni su base nazionale/internazionale. Questo progetto inoltre si propone di contribuire ad una migliore caratterizzazione molecolare di un numero crescente di soggetti con EE e prevede anche la possibilità di eseguire il sequenziamneto dell’intero esoma in un numero limitato di casi con fenotipidi emocromatosi che al momento restano non spiegati.
Hereditary Hemochromatosis (HHC) is one of the most common genetic diseases in Caucasians, as it can involve up to 5 per 1,000 (0.5 percent) individuals. Early diagnosis is essential, and has greatly improved since the discovery of the HFE gene in 1996, with subsequent development of a simple genetic test for the common mutations C282Y and H63D. Indeed, the majority of HHC patients are C282Y homozygotes or C282Y/H63D compound heterozygotes, the genotypes that are considered diagnosticfor “classic” HFE-HHC. However, HHC is a genetically heterogeneous disease in which near 30 percent of patients do not have such genotypes, and are currently classified as having “non-HFE” HHC.Mutations in at least four other genes involved in modulation of the hepcidin-ferroportin axis, i.e. HAMP, HJV, TFR2, and SLC40A1 have been reported to contribute to the disease expressionin such patients. At variance with HFE, mutations in thesegenes are typically “private”, i.e. limited to just few individuals, making unfeasible the use of standardized tests for the molecular diagnosis. Recent breakthrough of new techniques collectively known as “Next Generation Sequencing” (NGS) allow DNA sequencing with unprecedented rapidity at constantly declining costs. This project was aimed to develop a targeted NGS-based testfor sequencing the five hemochromatosis genes,and then to explore its performance in unravelingpotentially pathogenic variants in HHC patients, particularly in those cases that remained unexplained after first level genetic test. We studied 47 patients with relevant biochemical signs of iron overload (IO) and non-diagnostic first level genetic test suggesting a possible “non-HFE” HHC. This was defined as the absence of the C282Y and H63D mutations, or simple heterozygosity for each of them, or even H63D homozygosis.The five HHC genes were captured by Halo-Plex™ technology, and then sequenced using a NGS platform (IlluminaHiSeq 1000). Sequenced reads were aligned against human reference HG19 and analyzed by GoldenHelix™ software to annotate all the variants possibly involved in the disease. In IO patients a large number of new non-synonymous variants (according to bioinformatics tools based on publicly available databases including the 1000-genomes project) were found. Many of them were relatively frequent and detected also in controls, thus being considered likely “non-pathogenic”, unless clearly enriched in patients. On the other hand, some rare variants (i.e. limited to a single or very few individuals), particularly in SCL40A1, TFR2, and HFE, were found exclusively in patients, and could be considered “potentially pathogenic”. Among the identified variants 8 were apparently new, i.e. not reported in the following databases: dbSNPs, 1000 genome, OMIM and ESP Databases. Importantly, new rare variants that explained good phenotype/genotype correlation in patients with negative first level genetic and considered to be potentially pathogenic were detected. The combination of the Halo-Plex™ approach with NGS platform and GoldenHelix™ algorithm appears a suitable approach for a better molecular characterization of patients with unexplained HHC phenotype, and could represent a good option for second level genetic testing in referral centers. However, establishing the clinical relevance of NGS-detected “novel” genetic variants in a prevalently autosomal recessive disorder like HHC remains a difficult task, requiring further functional studies and national/international collaborative efforts. This project is also expected to significantly contribute to better characterization of the molecular basis of HHC, and will include the possibility to perform Whole Exome Sequencing (WES) in few cases with currently unexplained HHC-like phenotypes.

Hereditary Hemochromatosis (HH) is a disorder where iron and ferritin concentrations in a patient's blood are much higher than normal healthy levels. The main therapeutic intervention for individuals with HH is removing 300-500 mL of blood every few months to maintain ferritin concentration within acceptable ranges. The blood collected during these venesections is usually discarded as there is a belief that blood with high levels of ferritin are not suitable for blood transfusion purposes. Australian Red Cross Blood Services voluntarily collects blood from donors for subsequent use in blood transfusion. Annually more than 700 thousand units are transfused within Australia and there is a constant need for new donors given the significant imbalance between supply and demand of blood products. Besides red cell transfusions, the Red Cross also issues donor blood for development of many other blood products essential for patient health care. The HH blood can currently be used for other blood products if not for red cell transfusion. However, there is evidence to suggest that there is no significant difference between the red cells of the normal healthy population compared to those from HH patients. Australian Red Cross has developed a mobile computer application (High Ferritin “app”) as they have started collecting blood from HH patients. Though there is little or no awareness about the existence and use of this High Ferritin app in general HH population, their doctors and nurses collecting their blood for therapeutic purposes. This chapter describes possibility of saving and utilizing the blood collected from hemochromatosis patients for therapeutic purposes. A national hemochromatosis patients registry, in collaboration with High Ferritin app (HFa) developed by Australian Red Cross Blood Services, accessible to the patients, their doctors and Red Cross Blood Collection Sservices 24 hours a day anywhere in the country can allow the patients to donate the blood collected for therapeutic purposes at any affiliated blood collection center in the country after they automatically get a message either by email or text message after their blood results have been reviewed by their doctor and they are required to go for venesection.

Introdução: A Hemocromatose hereditária (HH) é uma mutação autossômica recessiva que resulta em sobrecarga de ferro. Sabe-se que essa alteração no metabolismo do ferro é causa de diversas doenças que levam seus portadores ao óbito, entre elas tem-se cirrose, diabetes, insuficiência cardíaca congestiva e carcinoma hepatocelular (CHC). Objetivos: Identificar evidências na literatura sobre a relação entre hemocromatose hereditária e a incidência de carcinoma hepatocelular. Metodologia: Através de uma revisão integrativa de literatura, encontrou-se 363 artigos nas bases de dados Pubmed, Scielo e Lilacs com o uso dos descritores contidos no Descritores em Ciências da Saúde: “Iron Overload”, “Hepatocellular Carcinoma” e “Hemochromatosis”. Foram incluídos artigos oriundos de ensaios clínicos, artigos originais, estudos observacionais e de avaliação, publicados nos anos de 2015 a 2021, nos idiomas inglês e português. Excluiu-se artigos desenvolvidos a partir de testes em animais. Resultados: A homozigose para o polimorfismo CP282Y do gene HFE demonstrou-se como um potente fator para a predisposição ao risco de neoplasias hepáticas. Os estudos mostram que a sobrecarga e deposição de ferro nas células hepáticas gera fibrose avançada e cirrose, que são as principais causas de CHC. Foi constatado que alguns pacientes com HH, principalmente quando não tratada, podem desenvolver o carcinoma hepatocelular, mesmo sem a presença da cirrose. Além disso, indivíduos com HH têm um risco a longo prazo de 20 a 200 vezes maior de desenvolver o CHC, devido a deposição de ferro no tecido hepático e a presença de radicais livres, como a hidroxila, que aumentam a incidência de câncer. Conclusão: A hemocromatose hereditária aumenta significativamente as chances de o indivíduo desenvolver o CHC o qual é umas das principais causas de morte prematura nos portadores dessa condição.