New Mutations in HFE2 and TFR2 Genes Causing Non HFE-Related Hereditary Hemochromatosis

Hereditary haemochromatosis: Prevalence and characterization of the disease in a tertiary hospital in Aragon, Spain

BACKGROUND

The main genetic cause of iron overload is haemochromatosis (HC). In recent years, the study of non-HFE genes (HFE2, HJV, HAMP, TRF2, SLC40A1, and BMP6) has become relevant thanks to next-generation sequencing (NGS) and multiplex ligation-dependent probe amplification (MLPA) techniques. Our objectives were to estimate the prevalence of both HFE (C282Y/HY63D variants) and non-HFE variants attending a tertiary hospital in Aragón, to predict the effect of the variants on the protein, and to establish a genotype-phenotype correlation evaluating with the clinical context.

METHODS

Retrospective descriptive study from 2006 to 2020 of patients attended at genetic consultation in a reference hospital for HC in Aragon. We calculated prevalence of HFE and non-HFE variants. We analysed non-HFE genes (HFE2, HJV, HAMP, TRF2, SLC40A1, and BMP6), used bioinformatics tools, consulted different databases and measured clinical parameters (laboratory and imaging).

RESULTS

The prevalence of C282Y homozygous was 5.95% respect the total of cases and 0.025% respect our population. The prevalence of non-HFE HC variants was 1.94% respect the total of cases and 0.008% respect our population. We found 27 variants in non-HFE genes and 4 in HFE gene, of which 6 were classified as variant of uncertain clinical significance (VUS), or likely pathogenic or pathogenic according to the ACMG classification criteria.

CONCLUSION

Our prevalence results are as expected, and similar to those obtained by other studies. Although some of the genetic findings explain the clinical symptoms of some of our patients, we remain have a high number of patients without a clear molecular diagnosis.

Hepatitis B Virus-Associated Liver Carcinoma: The Role of Iron Metabolism and Its Modulation

Hepatitis B virus (HBV) infection is a significant contributor to the development of hepatocellular carcinoma (HCC), a leading cause of cancer-related mortality worldwide. Iron, a central co-factor in various metabolic pathways, plays an essential role in liver function, but its dysregulation can lead to severe health consequences. Accumulation of iron within hepatic cells over time is linked to increased liver injury and is strongly associated with sensitive exposure to a range of conditions, including cirrhosis, fibrosis and ultimately, HCC. This review explores the intricate interplay between iron metabolism and HCC within the context of HBV infection. Hepatic iron overload can arise from liver injury and disruptions in iron homeostasis, causing hepatic necrosis, inflammation, and fibrosis, ultimately culminating in carcinogenesis. Moreover, alterations in serum iron components in HBV-related scenarios have been observed to impact the persistence of HBV infection. Notably, the progression of HBV-associated liver damage exhibits distinct characteristics at various stages of liver disease. In addition to elucidating the complex relationship between iron metabolism and HCC in the context of HBV infection, this review also investigates the prognostic implications of systemic iron levels for HCC. Furthermore, it aims to provide a comprehensive understanding of the intricate interplay between iron metabolism and HCC, extending the discussion to the context of hepatitis C virus (HCV) infection. By shedding light on these multifaceted connections, this review aims to contribute to our understanding of the pathogenesis of HBV-associated HCC and potentially identify novel therapeutic avenues for intervention.

Cardiac Manifestations of Hemochromatosis

Cardiac hemochromatosis, a consequence of primary or secondary iron-overload conditions, poses a threat to patient health, leading to cardiomyopathy and heart failure. This review aims to compile comprehensive information on cardiac hemochromatosis, elucidating its pathophysiology, clinical presentation, diagnosis, and management strategies. Primary and secondary hemochromatosis, genetic and acquired forms, can result in cardiotoxicity by means of iron dysregulation. Diagnostic tools, including biochemical markers, electrocardiography, echocardiography, and magnetic resonance imaging (MRI), are utilized for early detection as well as long-term monitoring post-treatment. For treatment options, phlebotomy is the standard, but for some patients (such as those with anemia), chelation therapy is an alternative option. Other potential therapies include erythrocytapheresis, calcium channel blockers, and hepcidin-targeted approaches, for which more research is needed to understand cardiac function benefits. With the onset of cardiac symptoms, patient health rapidly deteriorates. Thus, timely intervention to mitigate associated morbidity and mortality by means of screening can promote and prolong patient survival.

Novel mutation of transferrin receptor 2 causing hereditary hemochromatosis type 3 in a Japanese patient

Hereditary hemochromatosis (HH) is recognized as a progressive iron-storage disorder, and leading to severe organ impairments, including liver cirrhosis. Hereditary hemochromatosis type 3 arises from mutations in the transferrin receptor 2 (TFR2) gene. However, HH type 3 is rare in Asia, and information regarding genetic mutations and associated phenotypes remains limited. Here, we reported the case of a Japanese patient with HH type 3, with a novel homozygous mutation of the TFR2 gene. A 69-year-old woman presented to our hospital with hand joint pain and was referred due to liver impairment. Viral hepatitis and autoimmune liver diseases were ruled out. However, the transferrin saturation was 92.2%, and the serum ferritin level was 1611.8 ng/mL. Additionally, abdominal computed tomography showed diffuse increased density of the liver parenchyma. Abdominal magnetic resonance imaging also suggested iron deposition. There is no history of prior treatments involving blood transfusions or iron agents. Her parents were involved in a consanguineous marriage, prompting genetic testing. She had a homozygous novel mutation, c.1337G>A (p.G446E), in the TFR2 gene. Serum hepcidin-25 level was decreased to 2.9 ng/mL. According to the American Society of Medical Genetics and Genomics guideline, the mutation was classified as likely pathogenic, leading to the diagnosis of HH type 3. Following phlebotomy, her arthritis resolved, and serum transaminase levels were normalized. This case marks the first demonstration of homozygous mutation, c.1337G>A (p.G446E), in the TFR2 gene in patients with HH type 3.

[Diagnosis and treatment of iron overload]

Etiological investigation of hyperferritinemia includes a full clinical examination, with the measurement of waist circumference, and simple biological tests including transferrin saturation. The classification between hyperferritinemia without iron overload (inflammation, excessive alcohol intake, cytolysis, L-ferritin mutation) or with iron overload is then relatively easy. Dysmetabolic iron overload syndrome is the most common iron overload disease and is defined by an unexplained serum ferritin level elevation associated with various metabolic syndrome criteria and mild hepatic iron content increase assessed by magnetic resonance imaging. Bloodlettings are often poorly tolerated without clear benefit. Type 1 genetic hemochromatosis (homozygous C282Y mutation on the HFE gene) leads to iron accumulation through an increase of dietary iron absorption due to hypohepcidinemia. More than 95% of hemochromatosis are type 1 hemochromatosis but the phenotypic expression is highly variable. Elastography is recommended to identify advanced hepatic fibrosis when serum ferritin exceeds 1000μg/L. Life expectancy is normal when bloodlettings are started early. Ferroportin gene mutation is an autosomal dominant disease with generally moderate iron overload. Chelators are used in iron overload associated with anaemia (myelodysplastic syndromes or transfusion-dependent thalassemia). Chelation is initiated when hepatic iron content exceeds 120μmol/g. Deferasirox is often used as first-line therapy, but deferiprone may be of interest despite haematological toxicity (neutropenia). Deferoxamine (parenteral route) is the treatment of choice for severe iron overload or emergency conditions.

A Novel Mutation of Transferrin Receptor 2 in a Chinese Pedigree With Type 3 Hemochromatosis: A Case Report

Type 3 hereditary hemochromatosis (HH) is a rare form of HH characterized by genetic mutation in the TFR2 gene. Clinical features reported in patients with type 3 HH include abnormal liver function, liver fibrosis, cirrhosis, diabetes, hypogonadism, cardiomyopathy, and skin pigmentation. Since its original description in 2000, 33 pathogenic TFR2 mutations associated with HH have been described until now. Here, we first reported a Chinese pedigree of TFR2-related hemochromatosis with a novel compound heterozygous mutation c.1288G > A (p.G430R)/c.960T > A (p.Y320X). Interestingly, different phenotypes were reported although the proband and his sister shared the same gene mutation. This inconsistency between genotypes and phenotypes indicates multifactorial etiology contributing to the development of HH. Our report broadens the mutation spectrum of the TFR2 gene associated with HH.