Screening for hereditary haemochromatosis in patients undergoing knee arthroplasty

Aims Hereditary haemochromatosis is a genetic disorder that is caused by several known mutations in the human homeostatic iron regulator protein ( HFE) gene. Abnormal accumulation of iron causes a joint disease that resembles osteoarthritis (OA), but appears at a relatively younger age and is accompanied by cirrhosis, diabetes, and injury to other organs. Increased serum transferrin saturation and ferritin levels are known markers of haemochromatosis with high positive predictive values. Methods We have retrospectively analyzed the iron studies of a cohort of 2,035 patients undergoing knee joint arthroplasty due to OA. Results No patients had HFE gene C282Y, S65C, or H63D mutations testing. In total, 18 patients (2.96%) of the male cohort and 51 (3.58%) of the female cohort had pathologically increased ferritin levels that may be indicative of haemochromatosis. Seven patients (0.34%) had serum transferrin saturation above 45%. Conclusion The awareness for the diagnosis of this disorder in Orthopaedics is low and needs improvement. Osteoarthritic patients undergoing knee arthroplasty should be routinely screened for haemochromatosis by iron studies and referred to genetic testing when needed. Level of evidence: Level III - Retrospective cohort study. Cite this article: Bone Jt Open 2021;2(12):1062–1066.

H63D: The Other Mutation (2021 version)

In 2010, the Iron Disorders Institute published the first seminal article on the underestimated risk of a homozygous HFE gene H63D mutation. This short but important article has lost none of its relevance. Since it is in danger of being forgotten and disappearing from more and more websites, we are publishing a reprint of the still seminal article, expanded with some new findings.

CBIO-06. CELL INTRINSIC HFE DRIVES SEX-SPECIFIC GLIOBLASTOMA GROWTH

Iron is an essential element required for a number of cellular processes and can contribute to malignant transformation and tumor expansion. In glioblastoma (GBM), tumor cells have been shown to modulate expression of iron-associated proteins to enhance iron uptake from the surrounding microenvironment, driving proliferation and tumor growth. The homeostatic iron regulatory (HFE) gene encodes a transmembrane glycoprotein that aids in iron homeostasis by modulating iron uptake and release. HFE is upregulated in GBM tumors compared to non-tumor brain and expression of HFE increases with tumor grade. Furthermore, HFE mRNA expression is associated with significantly reduced survival specifically in female patients with GBM. However, it is unclear how HFE impacts sex-specific GBM growth. To interrogate the underlying mechanism of HFE-mediated sex differences, we employed genetic loss and gain of function approaches using syngeneic mouse glioma models. We observed significant alterations in the expression of several iron-associated genes with Hfe knockdown or overexpression, suggesting global disruption of iron homeostasis. We found that knockdown of Hfe decreased cell number and increased apoptosis in vitro and led to a significant impairment of tumor growth in vivo, with a more pronounced effect seen in female mice. Conversely, overexpression of Hfe increased cell number and significantly decreased survival only in female animals. These findings support the hypothesis that Hfe is a critical regulator of cellular iron status and contributes to tumor aggression in a sex-dependent manner. These data also suggest an unexplored link between cell intrinsic iron signaling and sex-specific microenvironmental and immune responses, which is the focus of ongoing studies.

Hfe Gene Knock-Out in a Mouse Model of Hereditary Hemochromatosis Affects Bodily Iron Isotope Compositions

Hereditary hemochromatosis is a genetic iron overload disease related to a mutation within the HFE gene that controls the expression of hepcidin, the master regulator of systemic iron metabolism. The natural stable iron isotope composition in whole blood of control subjects is different from that of hemochromatosis patients and is sensitive to the amount of total iron removed by the phlebotomy treatment. The use of stable isotopes to unravel the pathological mechanisms of iron overload diseases is promising but hampered by the lack of data in organs involved in the iron metabolism. Here, we use Hfe−/− mice, a model of hereditary hemochromatosis, to study the impact of the knock-out on iron isotope compositions of erythrocytes, spleen and liver. Iron concentration increases in liver and red blood cells of Hfe−/− mice compared to controls. The iron stable isotope composition also increases in liver and erythrocytes, consistent with a preferential accumulation of iron heavy isotopes in Hfe−/− mice. In contrast, no difference in the iron concentration nor isotope composition is observed in spleen of Hfe−/− and control mice. Our results in mice suggest that the observed increase of whole blood isotope composition in hemochromatosis human patients does not originate from, but is aggravated by, bloodletting. The subsequent rapid increase of whole blood iron isotope composition of treated hemochromatosis patients is rather due to the release of hepatic heavy isotope-enriched iron than augmented iron dietary absorption. Further research is required to uncover the iron light isotope component that needs to balance the accumulation of hepatic iron heavy isotope, and to better understand the iron isotope fractionation associated to metabolism dysregulation during hereditary hemochromatosis.

Bioinformatics and wet laboratory analysis of rs1800562 to predict genetic aetiology of iron overload in Nigeria

Introduction/Objective The most reported single nucleotide polymorphism (SNP) of the HFE gene is rs1800562, representing the substitution of Adenine for Guanine at position 847 of the HFE gene. This has been widely implicated in hereditary haemochromatosis and other conditions like altered cholesterol balance, Alzheimer’s disease and cutaneous photosensitivity. Abnormal HFE protein resulting from the mutant HFE gene leads to formation of excess iron which has been postulated as likely mechanism for these diseases. Although there is evidence of iron overload in Africans, only few studies have explored possible genetic causes, and prevalence of rs1800562 is not known in West African population. Hence the need to determine the prevalence of rs1800562 in Nigeria using computational and wet laboratory approach. Methods/Case Report Details of rs1800562 were retrieved from Ensembl Genome Browser version 99. Severity of the consequences of this SNP on protein product was determined using bioinformatics tools including SIFT, Polyphen, Mutation Assessor, HOPE, I-mutant and MutPred2. Genotyping of rs1800562 was done In silico using restriction fragment length polymorphism (RFLP). Primer3plus was used for primer design, NCBI BLAST and SMS were used for primer validation. We used Webcutter 2.0 to determine suitable restriction enzymes. The genotyping was simulated using USCS virtual PCR and RestrictionMapper. Whole blood samples were obtained from 200 participants selected randomly from a pool of blood donors. DNA was extracted and flanking region of rs1800562 was amplified. The amplified product was digested by RSA1and fragments examined on agarose gel electrophoresis. Results (if a Case Study enter NA) The MAF was found to be 0.01 globally and 0.02 in Africa. In the two Nigerian population examined (Yoruba and Esan population), MAF was 0.00. Mutation Assessor and SIFT Polyphen consistently predicted the mutation to be of severe consequences. Analysis on HOPE, I-mutant and Mutpred2 revealed loss of protein stability, change in net charges affecting the HFE protein localization and its interaction with other proteins. All the participants in the wet laboratory analysis were homozygous for the wild type allele of rs1800562 (MAF=0). Conclusion This study confirmed the In silico prediction of the absence of rs1800562 in Nigeria. Future studies should focus on other SNPs of the HFE gene as well as other gene involved in iron metabolism.

The Role of the Trabecular Bone Score in the Assessment of Osteoarticular Disorders in Patients with HFE-Hemochromatosis: A Single-Center Study from Poland

Type 1 hereditary hemochromatosis (HH) is an autosomal, recessive genetic entity with systemic iron overload. Iron homeostasis disorders develop as a result of HFE gene mutations, which are associated with hepcidin arthropathy or osteoporosis and may cause permanent disability in HH patients despite a properly conducted treatment with phlebotomies. In this study, selected parameters of calcium and phosphate metabolism were analyzed in combination with the assessment of bone mineral density (BMD) disorders in patients from northern Poland with clinically overt HFE-HH. BMD was determined by a dual-energy X-ray absorptiometry (DXA) test with the use of the trabecular bone score (TBS) function. The study included 29 HH patients (mean age = 53.14 years) who were compared with 20 healthy volunteers. A significantly lower TBS parameter and serum 25-OH-D3 concentration, a higher concentration of intact parathormone and more a frequent occurrence of joint pain were found in HH patients compared with the control group. In HH patients, the diagnosis of liver cirrhosis was associated with lower serum 25-OH-D3 and osteocalcin concentrations. In HH, DXA with the TBS option is a valuable tool in the early assessment of the bone microarchitecture and fracture risk. A supplementation of vitamin D, monitoring its concentration, should be considered especially in HH patients with liver damage and liver cirrhosis.

HEREDITARY HEMOCHROMATOSIS AND JAK2-POSITIVE POLYCYTHEMIA VERA

A 59-year-old male was diagnosed with JAK2-positive Polycythemia Vera. Subsequently, further lab testing revealed elevated ferritin and iron saturation. Genetic testing for HFE gene mutation screen revealed that the patient was positive for heterozygous C282Y mutation. The patient was ultimately diagnosed with both Polycythemia Vera and Hereditary Hemochromatosis.

HFE Genotype, Ferritin Levels and Transferrin Saturation in Patients with Suspected Hereditary Hemochromatosis

HFE hemochromatosis is characterized by increased iron absorption and iron overload due to variants of the iron-regulating HFE gene. Overt disease is mainly associated with homozygosity for the C282Y variant, although the H63D variant in compound heterozygosity with C282Y (C282Y/H63D) contributes to disease manifestation. In this observational study, we describe the association between biochemical findings, age, gender and HFE genotype in patients referred from general practice to a tertiary care referral center for diagnostic workup based on suspected hemochromatosis due to persistent hyperferritinemia and HFE variants. C282Y and H63D homozygosity were, respectively, the most and least prevalent genotypes and we found a considerable variation in transferrin saturation and ferritin levels independent of HFE genotype, which may indeed represent a diagnostic challenge in general practice. While our results confirm C282Y homozygosity as the major cause of iron accumulation, non-C282Y homozygotes also displayed mild to moderate hyperferritinemia with median ferritin levels at 500-700 µg/L, well above the reference cut-off. Such findings have traditionally been ignored in the clinic, and initiation of iron depletion has largely been restricted to C282Y homozygotes. Nevertheless, superfluous iron can aggravate pathogenesis in combination with other diseases and risk factors, such as inflammation, cancer and hepatopathy, and this possibility should not be neglected by clinicians.

Chronic hepatitis B in children carried out of the hemochromatosis gene HFE

Purpose: to establish the frequency and clinical significance of mutant variations of the HFE gene polymorphism in chronic hepatitis B (CHB) in children with iron overload syndrome (IOS).Materials and methods: 60 children with chronic hepatitis B with iron overload syndrome (IOS) were examined. When distributing children into groups, we took into account the criteria we developed for assessing the degree of life expectancy in children with CHB: CST>0.5 – mild degree of life expectancy (43,3% of children), CST˃0.5 – mild degree of life expectancy (43,3% of children), CST˂0,5 – moderate severity of life expectancy (31,7% of children) and CST˂0,2 – severe degree of SPL (25,0%). Virological verification of HBV was performed by ELISA and PCR. Using PCR Real Time and molecular genetic analysis, HFE gene C282Y, H63D, S65C mutations were detected from amplified DNA using the PRONTO Hemochromatosis reagent kit (Israel). The transferrin saturation coefficient (CST) was calculated using the formula CST = sTfR / log10.Ft. Results:Results: The study of the hemochromatosis gene HFE showed that the overwhelming majority (84,0%) of children with CHB with IOS were carriers of heterozygous, phenotypically different, mutant types. And only 16,0% of sick children were homozites of the wild (normal) HFE gene. Analysis of the phenotypic polymorphism of the hemochromatosis gene HFE revealed the presence of three point heterozygous mutations: H63D, S65C and combined variations in H63D / S65C, the latter of which is associated with severe forms of CHB and severe IOS.Conclusion. Children with CHB with IOS are characterized by a high incidence of heterozygous mutations in the HFE gene, the phenotypic manifestations of which were S65C, H63D, H63D / S65C. The comparability of the heterozygous combined mutation H63D / S65C with severe forms of CHB and a severe degree of IOS gives grounds to consider this phenotype of the HFE gene as a factor in the progression of the disease.

Frequency of occurrence of genetic polymorphisms associated with sports success in elite athletes in team sports

Objective: to evaluate the frequency of occurrence of polymorphisms rs1815739 (ACTN3 gene), rs2016520 (PPARD gene), rs1042713 (ADRB2 gene), rs1799945 (HFE gene) in athletes of high­performance sports.Materials and methods: genotyping was performed using allele­specific amplification with real­time detection of the results and using TaqMan probes.Results: a higher frequency of alleles associated with endurance was found: the t allele of the rs1815739 polymorphism (ACTN3 gene), the g allele of the rs2016520 polymorphism (PPARD gene), the g allele of the rs1042713 polymorphism (ADRB2 gene), and the g allele of the rs1799945 polymorphism (HFE gene) in athletes of game sports.Conclusion: the results of genotyping of polymorphisms associated with endurance in the examined athletes showed a higher frequency of occurrence than in the population as a whole.