Common conditions associated with hereditary haemochromatosis genetic variants: cohort study in UK Biobank

Incidence of liver complications with hemochromatosis-associated HFE p.C282Y homozygosity: The role of central adiposity

BACKGROUND AND AIMS

The HFE p.C282Y+/+ (homozygous) genotype and central adiposity both increase liver disease and diabetes risks, but the combined effects are unclear. We estimated waist-to-hip ratio (WHR) associations with incident clinical outcomes in routine care in p.C282Y+/+ participants in the UK Biobank community cohort.

APPROACH AND RESULTS

Baseline WHR data available in 1297 male and 1602 female p.C282Y+/+ with 13.3-year mean follow-up for diagnoses. Spline regressions and Cox proportional hazard models were adjusted for age and genetic principal components. Cumulative incidence was from age 40 to 80 years. In p.C282Y+/+ males, there were positive linear WHR relationships for hospital inpatient-diagnosed liver fibrosis/cirrhosis ( p = 2.4 × 10 -5 ), liver cancer ( p = 0.007), non-alcoholic fatty liver disease ( p = 7.7 × 10 -11 ), and type 2 diabetes ( p = 5.1 × 10 -16 ). The hazard ratio for high WHR in p.C282Y+/+ males (≥0.96; 33.9%) was 4.13 for liver fibrosis/cirrhosis (95% CI: 2.04-8.39, p = 8.4 × 10 -5 vs. normal WHR); cumulative age 80 incidence 15.0% (95% CI: 9.8%-22.6%) versus 3.9% (95% CI: 1.9%-7.6%); for liver cancer, cumulative incidence was 9.2% (95% CI: 5.7%-14.6%) versus 3.6% (95% CI: 1.9%-6.6%). Hemochromatosis was diagnosed in 23 (96%) of the 24 high WHR p.C282Y+/+ males with incident fibrosis/cirrhosis. High WHR (≥0.85; 30.0%) p.C282Y+/+ females had raised hazards for liver fibrosis/cirrhosis (hazard ratio = 9.17, 95% CI: 2.51-33.50, p = 3.8 × 10 -7 ) and Non-alcoholic fatty liver disease (hazard ratio = 5.17, 95% CI: 2.48-10.78, p = 1.2 × 10 -5 ). Fibrosis/cirrhosis associations were similar in the subset with additional primary care diagnoses.

CONCLUSIONS

In p.C282Y+/+ males and females, increasing WHR is associated with substantially higher risks of liver complications. Interventions to reduce central adiposity to improve these outcomes should be tested.

Novel mechanistic insights into the comorbidity of anemia and rheumatoid arthritis: Identification of therapeutic targets

OBJECTIVES

To investigate the mechanisms underlying the comorbidity of anemia and rheumatoid arthritis (RA) and identify promising therapeutic targets.

METHODS

We assessed the phenotypic linkage between anemia and RA. Using the largest genome-wide association studies (GWAS) summary statistics of European populations, we scrutinized the causal association and shared genetic architecture between the two conditions using multiple complementary approaches.

RESULTS

Logistic regression analysis confirmed a strong clinical association between anemia and RA. Using GWAS data, we identified a significant causal effect of RA on anemia and positive global genetic correlations between the two conditions (rg (genotype) = 0.28, P = 9.6 × 10-7; rg (gene expression) = 0.45, P = 2 × 10-3). After dividing the genome into 2495 independent regions, we identified 15 significant regions associated with both conditions, with 14 showing concordant effects. Fine-mapping at the SNP level revealed 72 % of RA-associated SNPs overlapped with anemia, most with concordant effects. Stratified Q-Q plots visualized the shared genetic enrichment, showing a 12-fold enrichment for RA conditional on anemia and 100-fold enrichment for anemia conditional on RA. Further analysis using conjFDR method pinpointed 14 pleiotropic loci, including several novel loci. Gene mapping identified 33 shared genes, with BLK and FAM167A further prioritized as the top two genes by SMR analysis. Enrichment analysis highlighted pathways related to inflammation, immune response, and iron metabolism. Blood and T cells showed significant tissue- and cell-type-specific enrichment.

CONCLUSIONS

This study provides novel insights into anemia-RA comorbidity mechanisms and identifies new drug targets for RA.

HFE-Related Hemochromatosis May Be a Primary Kupffer Cell Disease

Iron overload can lead to increased deposition of iron and cause organ damage in the liver, the pancreas, the heart and the synovium. Iron overload disorders are due to either genetic or acquired abnormalities such as excess transfusions or chronic liver diseases. The most common genetic disease of iron deposition is classic hemochromatosis (HH) type 1, which is caused by mutations of HFE. Other rare forms of HH include type 2A with mutations at the gene hemojuvelin or type 2B with mutations in HAMP that encodes hepcidin. HH type 3, is caused by mutations of the gene that encodes transferrin receptor 2. Mutations of SLC40A1 which encodes ferroportin cause either HH type 4A or HH type 4B. In the present review, an overview of iron metabolism including absorption by enterocytes and regulation of iron by macrophages, liver sinusoidal endothelial cells (LSECs) and hepatocyte production of hepcidin is presented. Hereditary Hemochromatosis and the current pathogenetic model are analyzed. Finally, a new hypothesis based on published data was suggested. The Kupffer cell is the primary defect in HFE hemochromatosis (and possibly in types 2 and 3), while the hepcidin-relative deficiency, which is the common underlying abnormality in the three types of HH, is a secondary consequence.

Identifying haemochromatosis patients with C282Y homozygosity from inpatient electronic patient records in England using a novel algorithm: a retrospective observational study

INTRODUCTION

Hereditary haemochromatosis (HH) is the most common genetic condition among populations of northern European ancestry, but it does not have a specific International Classification of Diseases 10th revision (ICD-10) diagnosis code. HH is commonly assigned the ICD-10 code E83.1 defined as 'disorders of iron metabolism'. However, the E83.1 diagnosis code is also applied to patients with transfusion-related iron overload and hyperferritinaemia from non-iron loading conditions. Venesection is the main treatment option for patients with HH and is assigned the Office of Population, Census and Surveys Classification of Interventions and Procedures, 4th revision (OPCS-4) code X36.2. We aimed to develop a novel algorithm to identify haemochromatosis patients with C282Y homozygosity from electronic patient records (EPR) using ICD-10 and OPCS-4 codes.

METHODS

The Hospital Episode Statistics Admitted Patient Care (APC) database was used to identify all patients with the ICD-10 code E83.1 from 1 April 2018 to 31 March 2023 in our NHS Trust. Case notes were reviewed to evaluate the presence of HH, genotype, medical history and associated procedures. Algorithms were generated using Stata MP V.18 by applying a combination of ICD-10 and OPCS-4 codes to all patients with the diagnosis code E83.1 including those without HH gene mutations.

RESULTS

A total of 9264 patient episodes were identified from the HES APC database corresponding to 787 unique patients: 479 (60.9%) C282Y homozygous, 107 (13.6%) C282Y/H63D compound heterozygotes, 42 (5.3%) other HH genetic mutations and 159 (20.2%) without any HH gene mutations. Six algorithms were developed to identify patients with HH within inpatient EPR, all of which showed improved positive predictive value (PPV) compared with the baseline cohort. The application of the OPCS-4 code for venesection (X36.2) in five of the algorithms resulted in large improvements in specificity and increased all their PPVs to >70%. Algorithms 4 and 6 had the best PPV at 74.3% and 74.4%, respectively, and included the removal of patients with ICD-10 codes associated with transfusion-related iron overload and other conditions treated with venesection.

CONCLUSION

These novel algorithms represent a more reliable method to detect haemochromatosis patients with C282Y homozygosity from EPR than the single ICD-10 code E83.1. It may be applied to large administrative datasets for investigation of HH in population studies.

Association of HFE genotypes with hemochromatosis-related phenotypes in the All of Us research program

Purpose

Type 1 hereditary hemochromatosis (HH) can result in iron overload and liver disease if not detected and treated early. Most cases are found among people homozygous for HFE p.Cys282Tyr variants. Compound heterozygosity with the HFE p.His63Asp variant is associated with disease to a lesser degree. We sought to examine the association of HFE variation with HH-related phenotypes and assess the prevalence of testing and diagnosis of HH using All of Us data.

Methods

We used data from 133,978 participants with genetic information linked to medical records. For different HFE genotypes, we examined the prevalence of HH diagnosis codes and related biochemical and clinical phenotypes.

Results

Among participants who were p.Cys282Tyr homozygotes, the prevalence of HH diagnosis codes was 22.6% among males and 15.6% among females. Serum transferrin-iron saturation measures were available only for 31.4% of males and 21.1% of females who were p.Cys282Tyr homozygotes. Liver disease, including cirrhosis or hepatocellular carcinoma, was present more among males who were p.Cys282Tyr homozygotes compared with males with no p.Cys282Tyr or p.His63Asp variants (15.5% vs 8.5%, P = .0001). Of the 71 participants who were p.Cys282Tyr homozygotes with indication of liver disease, 32 (45.1%) did not have a serum transferrin-iron saturation measure, and 37 (52.1%) did not have diagnosis codes for HH.

Conclusion

Limited serum transferrin-iron saturation measures or HH diagnosis codes among p.Cys282Tyr homozygotes, even those with liver disease, suggests potential undertesting and underdiagnosis of type 1 HH in clinical practice and a need for improved awareness, education, and testing around HH.

Introduction to Mendelian randomization

Mendelian randomization (MR), i.e. instrumental variable analysis using genetic instruments, is an approach that incorporates population genetics to improve causal inference. Given that genetics are randomly allocated at conception, this resembles the randomization process in randomized controlled trials and hence is more resistant to unobserved confounding compared to conventional observational studies (e.g. cohort studies). The seminar paper briefly described the origin of MR and its underlying assumptions (relevance, independence, and exclusion restriction). This was followed by introducing one sample MR designs (in which instrument-exposure and instrument-outcome associations are derived from the same sample) and one sample MR design (in which instrument-exposure and instrument-outcome associations are derived from different samples). The seminar paper then summarized key aspects of MR studies, such as instrument selection, data sources for conducting MR studies, and statistical analyses. Variations of MR design were also introduced, such as how this design can inform the effect of drug targets (drug target MR). The STROBE-MR checklist and relevant MR guidelines were introduced. The seminar paper concluded by discussing the credibility crisis of MR studies.

A decade of iron overload disorders and hemochromatosis: clinical and genetic findings from a specialized center in Colombia

Background

Iron overload disorders, including hereditary hemochromatosis (HH), are characterized by excessive iron accumulation, which can cause severe organ damage. HH is most associated with the C282Y mutation in Caucasian populations, but its prevalence and genetic profiles in Latin American populations remain underexplored.

Objectives

To describe the clinical manifestations, genetic profiles, and biochemical characteristics of patients with suspected iron overload disorders in a specialized hematology center in Cali, Colombia.

Methods

A retrospective observational study was conducted on 70 patients diagnosed with iron overload disorders between 2014 and 2024. Data on clinical presentation, laboratory results, imaging, and genetic mutations were collected. Statistical analyses, including chi-square tests and logistic regression, were used to evaluate factors associated with HH diagnosis.

Results

Male patients constituted 64.3% of the sample, with a mean age of 56.1 years at diagnosis. Fatigue (27.1%) and joint pain (17.1%) were the most common symptoms. Of the total sample, 32.9% were diagnosed with hemochromatosis. The H63D mutation was the most prevalent (52.2%), while the C282Y mutation was rare. A predominance of both slight (100.0%) and limitrophe (58.3%) iron overload was identified among patients with hemochromatosis (p = 0.036).

Conclusion

Colombian patients with iron overload disorders show clinical, epidemiological, and biochemical profiles consistent with global patterns, yet exhibit distinct genetic diversity. Notably, they have a low prevalence of the C282Y mutation and a higher prevalence of the H63D mutation, differing from European HH profiles. Despite elevated ferritin and transferrin saturation, no significant clinical symptoms were observed, suggesting potential delays in diagnosis. These findings highlight the need for early, region-specific diagnostic approaches to prevent complications like cirrhosis and underscore the importance of further genetic research across Latin America.

Mortality and risk of diabetes, liver disease, and heart disease in individuals with haemochromatosis HFE C282Y homozygosity and normal concentrations of iron, transferrin saturation, or ferritin: prospective cohort study

OBJECTIVES

To test whether haemochromatosis HFE C282Y homozygotes have increased risk of diabetes, liver disease, and heart disease even when they have normal plasma iron, transferrin saturation, or ferritin concentrations and to test whether C282Y homozygotes with diabetes, liver disease, or heart disease have increased mortality compared with non-carriers with these diseases.

DESIGN

Prospective cohort study.

SETTING

Three Danish general population cohorts: the Copenhagen City Heart Study, the Copenhagen General Population Study, and the Danish General Suburban Population Study.

PARTICIPANTS

132 542 individuals genotyped for the HFE C282Y and H63D variants, 422 of whom were C282Y homozygotes, followed prospectively for up to 27 years after study enrolment.

MAIN OUTCOME MEASURE

Hospital contacts and deaths, retrieved from national registers, covering all hospitals and deaths in Denmark.

RESULTS

Comparing C282Y homozygotes with non-carriers, hazard ratios were 1.72 (95% confidence interval (CI) 1.24 to 2.39) for diabetes, 2.22 (1.40 to 3.54) for liver disease, and 1.01 (0.78 to 1.31) for heart disease. Depending on age group, the absolute five year risk of diabetes was 0.54-4.3% in C282Y homozygous women, 0.37-3.0% in non-carrier women, 0.86-6.8% in C282Y homozygous men, and 0.60-4.80% in non-carrier men. When studied according to levels of iron, transferrin saturation, and ferritin in a single blood sample obtained at study enrolment, risk of diabetes was increased in C282Y homozygotes with normal transferrin saturation (hazard ratio 2.00, 95% CI 1.04 to 3.84) or ferritin (3.76, 1.41 to 10.05) and in C282Y homozygotes with normal levels of both ferritin and transferrin saturation (6.49, 2.09 to 20.18). C282Y homozygotes with diabetes had a higher risk of death from any cause than did non-carriers with diabetes (hazard ratio 1.94, 95% CI 1.19 to 3.18), but mortality was not increased in C282Y homozygotes without diabetes. The percentage of all deaths among C282Y homozygotes that could theoretically be prevented if excess deaths in individuals with a specific disease were eliminated (the population attributable fraction) was 27.3% (95% CI 12.4% to 39.7%) for diabetes and 14.4% (3.1% to 24.3%) for liver disease. Risk of diabetes or liver disease was not increased in H63D heterozygotes, H63D homozygotes, C282Y heterozygotes, or C282Y/H63D compound heterozygotes.

CONCLUSIONS

Haemochromatosis C282Y homozygotes with normal transferrin saturation and/or ferritin, not recommended for HFE genotyping according to most guidelines, had increased risk of diabetes. Furthermore, C282Y homozygotes with diabetes had higher mortality than non-carriers with diabetes, and 27.3% of all deaths among C282Y homozygotes were potentially attributable to diabetes. These results indicate that prioritising detection and treatment of diabetes in C282Y homozygotes may be relevant.

Novel loci and biomedical consequences of iron homoeostasis variation

Iron homoeostasis is tightly regulated, with hepcidin and soluble transferrin receptor (sTfR) playing significant roles. However, the genetic determinants of these traits and the biomedical consequences of iron homoeostasis variation are unclear. In a meta-analysis of 12 cohorts involving 91,675 participants, we found 43 genomic loci associated with either hepcidin or sTfR concentration, of which 15 previously unreported. Mapping to putative genes indicated involvement in iron-trait expression, erythropoiesis, immune response and cellular trafficking. Mendelian randomisation of 292 disease outcomes in 1,492,717 participants revealed associations of iron-related loci and iron status with selected health outcomes across multiple domains. These associations were largely driven by HFE, which was associated with the largest iron variation. Our findings enhance understanding of iron homoeostasis and its biomedical consequences, suggesting that lifelong exposure to higher iron levels is likely associated with lower risk of anaemia-related disorders and higher risk of genitourinary, musculoskeletal, infectious and neoplastic diseases.

Diagnosis and management of hereditary hemochromatosis: lifestyle modification, phlebotomy, and blood donation

The term hemochromatosis refers to a group of genetic disorders characterized by hepcidin insufficiency in the context of normal erythropoiesis, iron hyperabsorption, and expansion of the plasma iron pool with increased transferrin saturation, the diagnostic hallmark of the disease. This results in the formation of toxic non-transferrin-bound iron, which ultimately accumulates in multiple organs, including the liver, heart, endocrine glands, and joints. The most common form is HFE-hemochromatosis (HFE-H) due to p.Cys282Tyr (C282Y) homozygosity, present in nearly 1 in 200 people of Northern European descent but characterized by low penetrance, particularly in females. Genetic and lifestyle cofactors (especially alcohol and dysmetabolic features) significantly modulate clinical expression so that HFE-H can be considered a multifactorial disease. Nowadays, HFE-H is mostly diagnosed before organ damage and is easily treated by phlebotomy, with an excellent prognosis. After iron depletion, maintenance phlebotomy can be usefully transformed into a blood donation program. Lifestyle changes are important for management. Non-HFE-H, much rarer but highly penetrant, may lead to early and severe heart, liver, and endocrine complications. Managing severe hemochromatosis requires a comprehensive approach optimally provided by consultation with specialized centers. In clinical practice, a proper diagnostic approach is paramount for patients referred for hyperferritinemia, a frequent finding that reflects hemochromatosis only in a minority of cases.

Bone phenotyping of murine hemochromatosis models with deficiencies of Hjv, Alk2, or Alk3: The influence of sex and the bone compartment

Osteopenia is frequently observed in patients with iron overload, especially in those with HFE-dependent hereditary hemochromatosis (HH). Interestingly, not all mouse models of HH show bone loss, suggesting that iron overload alone may not suffice to induce bone loss. In this study, the bone phenotypes of Hjv-/- and hepatocyte-specific Alk2- and Alk3-deficient mice as additional mouse models of HH were investigated to further clarify, how high iron levels lead to bone loss and which signaling mechanisms are operational. Neither male nor female 12-week-old Hjv-/- mice had an altered trabecular or cortical bone mass or bone turnover, despite severe iron overload. Male 12-month-old Hjv-/- mice even presented with a higher femoral trabecular bone volume compared to wildtype mice. Similarly, female mice with hepatocyte-specific Alk2 or Alk3 deficiency did not show an altered bone phenotype at 3, 6, and 12 months of age. Male hepatocyte-specific Alk3-deficient mice also had a normal trabecular bone mass at all ages analyzed, despite showing increased bone resorption and decreased bone formation parameters. Interestingly, hepatocyte-specific Alk2-deficient mice showed reduced femoral trabecular bone at 6 months of age due to suppressed bone formation. Cortical thickness at the femur was reduced in both, 6-month-old male hepatocyte-specific Alk2- and Alk3-deficient mice. Raising hepatocyte-specific Alk2-deficient male mice on an iron-deficient diet rescued the bone phenotype. Taken together, despite iron overload, trabecular bone microarchitecture was not altered in mice deficient of Hjv or Alk3. Only male hepatocyte-specific Alk2-deficient mice showed site-specific lower trabecular and cortical bone mass at the femur, which was dependent on iron. Thus, bone loss does not correlate with the extent of iron overload in these mouse models, but may relate to the amount of iron-loaded macrophages, as precursors of osteoclasts, in the bone marrow.

Hemochromatosis neural archetype reveals iron disruption in motor circuits

Our understanding of brain iron regulation and its disruption in disease is limited. Excess iron affects motor circuitry, contributing to Parkinson's disease (PD) risk. The molecular mechanisms regulating central iron levels, beyond a few well-known genes controlling peripheral iron, remain unclear. We generated scores based on the archetypal brain iron accumulation observed in magnetic resonance imaging scans of individuals with excessive dietary iron absorption and hemochromatosis risk. Genome-wide analysis revealed that this score is highly heritable, identifying loci associated with iron homeostasis, and driven by peripheral iron levels. Our score predicted gait abnormalities and showed a U-shaped relationship with PD risk, identifying individuals with threefold increased risk. These results establish a hormetic relationship between brain iron and PD risk, where central iron levels are strongly determined by genetics via peripheral iron. This framework combining forward and reverse genetics is a powerful study design to understand genomic drivers underlying high dimensional phenotypes.

Investigation of BMP6 mutations in Brazilian patients with iron overload

BACKGROUND

Iron overload (IO) is a complex condition in which clinical, behavioral and genetic factors contribute to the phenotype. In multiethnic and non-Caucasian populations, mutations in HFE gene alone cannot explain IO in most of the cases, and additional genetic and environmental factors must be investigated. Bone Morphogenetic Proteins (BMPs) play a central role in iron homeostasis by modulating HAMP transcription through the signaling pathway that includes SMAD and HJV. In this study, we aimed to explore the clinical relevance of BMP6 mutations in a cohort of Brazilian patients with IO.

METHODS

41 patients with IO were evaluated. Blood samples were collected to analyze BMP6 mutations through New Sequence Generations (NGS). Frequency of variants and mutations were analyzed and correlated with clinical and environmental characteristics.

RESULTS

We identified BMP6 mutations in three patients with IO. The p.Arg257His mutation was identified in two patients and the p.Leu71Val mutation was identified in one patient. Two of these patients had additional risk factors for IO (HFE mutations and diabetes mellitus).

CONCLUSION

BMP6 mutations, when combined to other genetic and clinical risk factors, may contribute to IO. Functional studies and THE evaluation of large cohorts are necessary to fully address BMP6 role in IO.

Prospective cohort for early detection of liver cancer (Pearl): a study protocol

INTRODUCTION

Hepatocellular carcinoma (HCC) is the fastest-rising and fourth most common cause of cancer death worldwide. Liver cirrhosis is the largest underlying risk factor for HCC. Therefore, patients with cirrhosis should have regular ultrasound and biochemical screening to pick up early HCC. Early HCC can be cured; more advanced HCCs have limited treatment options and poor prognosis. Current screening methods are suboptimal with poor sensitivity in picking up early disease. In this study, the investigators aim to recruit people with liver cirrhosis into a Prospective cohort for early detection of liver cancer-the Pearl cohort. The investigators believe that by using state-of-the-art tests we can improve the detection of early HCC.

METHODS AND ANALYSIS

This is a UK-based prospective, longitudinal, diagnostic, prognostic, multicentre, non-CTIMP study. Aiming to recruit 3000 patients with liver cirrhosis without a HCC diagnosis, the Pearl cohort will be followed actively for 3 years from recruitment and then passively via registry data for ten years thereafter. Blood and urine samples will be taken and information from routine care will be gathered. These will be used to assess novel diagnostic approaches for the detection early HCC and to develop models to identify those most at risk for developing HCC.Participants will be linked to national UK health registries to ensure long-term capture of HCC incidence and other relevant endpoints. Approximately 75 patients are predicted to develop de novo HCC within the 3-year follow up period. After this period, the study teams will obtain data on participants for at least 10 years after the last contact. This cohort will help develop an understanding of the incidence of HCC in a UK population stratified by underlying cirrhosis aetiology.

ETHICS AND DISSEMINATION

Ethical approval has been granted by REC and the trial is registered on ClinicalTrials.gov. The results will be published in peer-reviewed journals and presented at relevant meetings.

TRIAL REGISTRATION NUMBER

NCT05541601.

Iron, hemochromatosis genotypes, and risk of infections: a cohort study of 142 188 general population individuals

ABSTRACT

It is unclear whether risk of infection is increased in individuals with hereditary hemochromatosis and in individuals with low or high plasma iron, transferrin saturation, or ferritin. Therefore, we tested whether high and low iron, transferrin saturation, and ferritin are associated with risk of infections observationally and genetically through HFE genotypes. We studied 142 188 Danish general population individuals. Iron, transferrin saturation, and ferritin were measured in 136 656, 136 599, and 38 020 individuals, respectively. HFE was genotyped for C282Y and H63D in 132 542 individuals. Median follow-up after study enrollment was 8 years (range, 0-38) for hospital and emergency room admissions with infections (n = 20 394) using the National Patient Register, covering all Danish hospitals. Hazard ratios for any infection were 1.20 (95% confidence interval [CI], 1.12-1.28) and 1.14 (95% CI, 1.07-1.22) in individuals with plasma iron ≤5th or ≥95th percentile compared with individuals with iron from 26th to 74th percentiles. Findings for transferrin saturation were similar, whereas infection risk was not increased in individuals with ferritin ≤5th or ≥95th percentile. Hazard ratios in C282Y homozygotes vs noncarriers were 1.40 (95% CI, 1.16-1.68) for any infection, 1.69 (95% CI, 1.05-2.73) for sepsis, and 2.34 (95% CI, 1.41-3.90) for death from infectious disease. Risk of infection was increased in C282Y homozygotes with normal plasma iron, transferrin saturation, or ferritin, and in C282Y homozygotes without liver disease, diabetes, and/or heart failure. In summary, low and high plasma iron and transferrin saturation were independently associated with increased infection risk. C282Y homozygotes had increased risk of any infection, sepsis, and death from infections. Even C282Y homozygotes with normal iron, transferrin saturation, or ferritin, not currently recommended for genotyping, had increased infection risk.

Population Screening for Hereditary Haemochromatosis-Should It Be Carried Out, and If So, How?

The Human Genome Project, completed in 2003, heralded a new era in precision medicine. Somewhat tempering the excitement of the elucidation of the human genome is the emerging recognition that there are fewer single gene disorders than first anticipated, with most diseases predicted to be polygenic or at least gene-environment modified. Hereditary haemochromatosis (HH) is an inherited iron overload disorder, for which the vast majority of affected individuals (>90%) have homozygosity for a single pathogenic variant in the HFE gene, resulting in p.Cys282Tyr. Further, there is significant benefit to an individual in identifying the genetic risk of HH, since the condition evolves over decades, and the opportunity to intervene and prevent disease is both simple and highly effective through regular venesection. Add to that the immediate benefit to society of an increased pool of ready blood donors (blood obtained from HH venesections can generally be used for donation), and the case for population screening to identify those genetically at risk for HH becomes more cogent. Concerns about genetic discrimination, creating a cohort of "worried well", antipathy to acting on medical advice to undertake preventive venesection or simply not understanding the genetic risk of the condition adequately have all been allayed by a number of investigations. So why then has HH population genetic screening not been routinely implemented anywhere in the world? The answer is complex, but in this article we explore the pros and cons of screening for HH and the different views regarding whether it should be phenotypic (screening for iron overload by serum ferritin and/or transferrin saturation) or genotypic (testing for HFE p.Cys282Tyr). We argue that now is the time to give this poster child for population genetic screening the due consideration required to benefit the millions of individuals at risk of HFE-related iron overload.

A brief communication of patients with homozygous C282Y mutation-related hereditary hemochromatosis

Hereditary hemochromatosis (HH) is an autosomal recessive inherited iron-loading disorder and is characterized by chronic hepatitis, cirrhosis, diabetes, and bronze skin. The hemochromatosis gene (C282Y homozygosity)-related hemochromatosis is the most common form of HH. The prevalence of HH is varied. Here, we defined six cases with C282Y homozygosity-related HH in a single center in Turkiye.

Case report: A rare case of hereditary hemochromatosis caused by a mutation in the HAMP gene in Fuyang, China

Hemochromatosis, also known as siderosis, is a disease caused by excessive iron deposition in human organs and tissues, resulting from iron metabolism disorders. It is clinically characterized by skin pigmentation (bronze color), liver cirrhosis, diabetes, weakness, and fatigue. Additional symptoms may include arthritis, hypothyroidism, heart failure, and sexual hypofunction. Clinical manifestations can vary from person to person, with a few patients showing no clinical manifestations, which makes the diagnosis difficult for clinicians. In this case report, we described hereditary hemochromatosis related to a mutation in the HAMP gene in Fuyang City, China, as a reference for clinicians. Hereditary hemochromatosis is rarely reported in China. Clinicians in China have relatively insufficient knowledge of this disease, which leads to frequent misdiagnosis. In this case report, we describe hereditary hemochromatosis related to HAMP gene mutation in Fuyang City, China, for the clinician's reference.

Noninvasive assessment of organ-specific and shared pathways in multi-organ fibrosis using T1 mapping

Fibrotic diseases affect multiple organs and are associated with morbidity and mortality. To examine organ-specific and shared biologic mechanisms that underlie fibrosis in different organs, we developed machine learning models to quantify T1 time, a marker of interstitial fibrosis, in the liver, pancreas, heart and kidney among 43,881 UK Biobank participants who underwent magnetic resonance imaging. In phenome-wide association analyses, we demonstrate the association of increased organ-specific T1 time, reflecting increased interstitial fibrosis, with prevalent diseases across multiple organ systems. In genome-wide association analyses, we identified 27, 18, 11 and 10 independent genetic loci associated with liver, pancreas, myocardial and renal cortex T1 time, respectively. There was a modest genetic correlation between the examined organs. Several loci overlapped across the examined organs implicating genes involved in a myriad of biologic pathways including metal ion transport (SLC39A8, HFE and TMPRSS6), glucose metabolism (PCK2), blood group antigens (ABO and FUT2), immune function (BANK1 and PPP3CA), inflammation (NFKB1) and mitosis (CENPE). Finally, we found that an increasing number of organs with T1 time falling in the top quintile was associated with increased mortality in the population. Individuals with a high burden of fibrosis in ≥3 organs had a 3-fold increase in mortality compared to those with a low burden of fibrosis across all examined organs in multivariable-adjusted analysis (hazard ratio = 3.31, 95% confidence interval 1.77-6.19; P = 1.78 × 10-4). By leveraging machine learning to quantify T1 time across multiple organs at scale, we uncovered new organ-specific and shared biologic pathways underlying fibrosis that may provide therapeutic targets.

Serum ferritin level is associated with liver fibrosis and incident liver-related outcomes independent of HFE genotype in the general population

BACKGROUND & AIMS

Hyperferritinemia reflects iron accumulation in the body and has been associated with metabolic disturbances and alcohol use, and is also a common finding in individuals diagnosed with liver disease. The major genetic regulator of iron metabolism is the HFE gene.

METHODS

The aim of this this study was to investigate the association between serum ferritin and liver fibrosis using the enhanced liver fibrosis (ELF) test, and the association between ferritin and liver-related outcomes in a Finnish population-based cohort of 6194 individuals (45% male, mean [± standard deviation] age, 52.9 ± 14.9 years; body mass index 26.9 ± 4.7 kg/m2). The effects of HFE variants on these associations were also evaluated.

RESULTS

Serum ferritin levels were significantly associated with liver fibrosis, as estimated by enhanced liver fibrosis (ELF) test in weighted linear regression analysis. Serum ferritin was significantly associated with both all liver-related outcomes (n = 92) and severe liver-related outcomes (n = 54) in weighted Cox regression analysis (hazard ratio [HR] per 1 SD, 1.11 [95% confidence interval (CI) 1.02-1.21]; p = 0.012 and HR 1.11 [95% CI 1.02-1.21]; p = 0.013, respectively). However, there was association neither between HFE risk variants and ELF test nor between HFE risk variants and liver-related outcomes.

CONCLUSION

Serum ferritin levels were associated with liver fibrosis and incident liver disease, independent of HFE genotype in the general population. Furthermore, data demonstrated that metabolic disturbances and alcohol use were major risk factors for hyperferritinemia.

SLCO1B1 Exome Sequencing and Statin Treatment Response in 64,000 UK Biobank Patients

The solute carrier organic anion transporter family member 1B1 (SLCO1B1) encodes the organic anion-transporting polypeptide 1B1 (OATP1B1 protein) that transports statins to liver cells. Common genetic variants in SLCO1B1, such as *5, cause altered systemic exposure to statins and therefore affect statin outcomes, with potential pharmacogenetic applications; yet, evidence is inconclusive. We studied common and rare SLCO1B1 variants in up to 64,000 patients from UK Biobank prescribed simvastatin or atorvastatin, combining whole-exome sequencing data with up to 25-year routine clinical records. We studied 51 predicted gain/loss-of-function variants affecting OATP1B1. Both SLCO1B1*5 alone and the SLCO1B1*15 haplotype increased LDL during treatment (beta*5 = 0.08 mmol/L, p = 6 × 10-8; beta*15 = 0.03 mmol/L, p = 3 × 10-4), as did the likelihood of discontinuing statin prescriptions (hazard ratio*5 = 1.12, p = 0.04; HR*15 = 1.05, p = 0.04). SLCO1B1*15 and SLCO1B1*20 increased the risk of General Practice (GP)-diagnosed muscle symptoms (HR*15 = 1.22, p = 0.003; HR*20 = 1.25, p = 0.01). We estimated that genotype-guided prescribing could potentially prevent 18% and 10% of GP-diagnosed muscle symptoms experienced by statin patients, with *15 and *20, respectively. The remaining common variants were not individually significant. Rare variants in SLCO1B1 increased LDL in statin users by up to 1.05 mmol/L, but replication is needed. We conclude that genotype-guided treatment could reduce GP-diagnosed muscle symptoms in statin patients; incorporating further SLCO1B1 variants into clinical prediction scores could improve LDL control and decrease adverse events, including discontinuation.

Clinical characteristics of HFE C282Y/H63D compound heterozygotes identified in a specialty practice: key differences from HFE C282Y homozygotes

BACKGROUND

Patients with p.C282Y homozygous (p.C282Y) HFE mutations are more likely to develop hemochromatosis (HC) than p.C282Y/p.H63D compound heterozygotes (p.C282Y/H63D).

RESEARCH DESIGN AND METHODS

We conducted a retrospective chart review of 90 p.C282Y and 31 p.C282Y/H63D patients at a referral practice to illustrate the differences in the natural history of the disease in these two HC cohorts.

RESULTS

Over a median follow-up of 17 years, p.C282Y had higher mean serum ferritin (1105 mg/dL vs. 534 mg/dL, p = 0.001) and transferrin saturations (75.3% vs. 49.5%, p = 0.001) at diagnosis. p.C282Y underwent more therapeutic phlebotomies (TP) till de-ironing (mean 24 vs. 10), had higher mean mobilized iron stores (4759 mg vs. 1932 mg), and required more annual maintenance TP (1.9/year vs. 1.1/year, p = 0.039). p.C282Y/H63D were more likely to have obesity (45.2% vs. 20.2%, p = 0.007) at diagnosis, with a non-significant trend toward consuming more alcohol. There was no significant difference in the development of HC-related complications between the two cohorts.

CONCLUSIONS

p.C282Y have a higher mobilizable iron and require more TP. p.C282Y/H63D likely require additional insults such as obesity or alcohol use to develop elevated ferritin. De-ironing may mitigate the risk of developing HC-related complications.

HFE genotypes, haemochromatosis diagnosis and clinical outcomes at age 80 years: a prospective cohort study in the UK Biobank

OBJECTIVES

HFE haemochromatosis genetic variants have an uncertain clinical penetrance, especially to older ages and in undiagnosed groups. We estimated p.C282Y and p.H63D variant cumulative incidence of multiple clinical outcomes in a large community cohort.

DESIGN

Prospective cohort study.

SETTING

22 assessment centres across England, Scotland, and Wales in the UK Biobank (2006-2010).

PARTICIPANTS

451 270 participants genetically similar to the 1000 Genomes European reference population, with a mean of 13.3-year follow-up through hospital inpatient, cancer registries and death certificate data.

MAIN OUTCOME MEASURES

Cox proportional HRs of incident clinical outcomes and mortality in those with HFE p.C282Y/p.H63D mutations compared with those with no variants, stratified by sex and adjusted for age, assessment centre and genetic stratification. Cumulative incidences were estimated from age 40 years to 80 years.

RESULTS

12.1% of p.C282Y+/+ males had baseline (mean age 57 years) haemochromatosis diagnoses, with a cumulative incidence of 56.4% at age 80 years. 33.1% died vs 25.4% without HFE variants (HR 1.29, 95% CI: 1.12 to 1.48, p=4.7×10-4); 27.9% vs 17.1% had joint replacements, 20.3% vs 8.3% had liver disease, and there were excess delirium, dementia, and Parkinson's disease but not depression. Associations, including excess mortality, were similar in the group undiagnosed with haemochromatosis. 3.4% of women with p.C282Y+/+ had baseline haemochromatosis diagnoses, with a cumulative incidence of 40.5% at age 80 years. There were excess incident liver disease (8.9% vs 6.8%; HR 1.62, 95% CI: 1.27 to 2.05, p=7.8×10-5), joint replacements and delirium, with similar results in the undiagnosed. p.C282Y/p.H63D and p.H63D+/+ men or women had no statistically significant excess fatigue or depression at baseline and no excess incident outcomes.

CONCLUSIONS

Male and female p.C282Y homozygotes experienced greater excess morbidity than previously documented, including those undiagnosed with haemochromatosis in the community. As haemochromatosis diagnosis rates were low at baseline despite treatment being considered effective, trials of screening to identify people with p.C282Y homozygosity early appear justified.

Penetrance, cancer incidence and survival in HFE haemochromatosis-A population-based cohort study

BACKGROUND AND AIMS

Haemochromatosis is characterized by progressive iron overload affecting the liver and can cause cirrhosis and hepatocellular carcinoma. Most haemochromatosis patients are homozygous for p.C282Y in HFE, but only a minority of individuals with this genotype will develop the disease. The aim was to assess the penetrance of iron overload, fibrosis, hepatocellular carcinoma and life expectancy.

METHODS

A total of 8839 individuals from the Austrian region of Tyrol were genotyped for the p.C282Y variant between 1997 and 2021. Demographic, laboratory parameters and causes of death were assessed from health records. Penetrance, survival, and cancer incidence were ascertained from diagnosed cases, insurance- and cancer registry data. Outcomes were compared with a propensity score-matched control population.

RESULTS

Median age at diagnosis in 542 p.C282Y homozygous individuals was 47.8 years (64% male). At genotyping, the prevalence of iron overload was 55%. The cumulative penetrance of haemochromatosis defined as the presence of provisional iron overload was 24.2% in males and 10.5% in females aged 60 years or younger. Among p.C282Y homozygotes of the same ages, the cumulative proportion of individuals without fibrosis (FIB-4 score < 1.3) was 92.8% in males and 96.7% in females. Median life expectancy was reduced by 6.8 years in individuals homozygous for p.C282Y when compared with population-matched controls (p = .001). Hepatocellular carcinoma incidence was not significantly higher in p.C282Y homozygotes than in controls matched for age and sex.

CONCLUSION

Reduced survival and the observed age-dependent increase in penetrance among p.C282Y homozygotes call for earlier diagnosis of haemochromatosis to prevent complications.

Pierre TG, Chen J, Frazer DM, Ramm LE, Ramm GA. Extrahepatic Iron Loading Associates With the Propensity to Develop Advanced Hepatic Fibrosis in Hemochromatosis

Background and Aims

Hemostatic iron regulator-hemochromatosis can result in progressive iron-loading and advanced hepatic fibrosis in some individuals. We studied total body and hepatic iron loading to determine whether the distribution of iron-loading influences the risk of advanced fibrosis.

Methods

One hundred thirty-eight men and 66 women with hemochromatosis who underwent liver biopsy for staging of hepatic fibrosis had evaluation of hepatic iron concentration (HIC), hepatic iron index (HIC/age), total body iron stores (mobilizable iron), and mobilizable iron/HIC ratio (a marker of total body iron relative to hepatic iron). The potential impact of liver volume on mobilizable iron stores was assessed using magnetic resonance imaging in a separate cohort of 19 newly diagnosed individuals with hemochromatosis.

Results

Of 204 biopsied subjects, 41 had advanced fibrosis and exhibited 60% greater accumulation of mobilizable iron relative to HIC (mean 0.070 ± 0.008 g Fe/[μmol Fe/g]) compared with 163 subjects with low-grade fibrosis (mean 0.044 ± 0.002 g Fe/[μmol Fe/g], P < .0001). Linear regression modeling confirmed a discrete advanced hepatic fibrosis phenotype associated with greater mobilizable iron stores relative to HIC. The ratios of the upper to lower 95% limits of the distributions of liver volumes and the mobilizable iron/HIC ratios were 2.7 (95% confidence interval 2.3-3.0) and 9.7 (95% confidence interval 8.0-11.7), respectively, indicating that the distribution of liver volumes is not sufficiently wide to explain the variability in mobilizable iron/HIC ratios, suggesting that significant extrahepatic iron loading is present in those with advanced hepatic fibrosis.

Conclusion

Advanced hepatic fibrosis develops in hemostatic iron regulator-hemochromatosis individuals who also have excessive extrahepatic mobilizable iron stores.

A Rare Case of Heterozygous C282Y Mutation Causing Hereditary Hemochromatosis With Acute Pancreatitis

Hereditary hemochromatosis (HH) is the most common autosomal recessive genetic disorder globally for Caucasians. HH is known as an iron metabolism disorder where there is an increase in iron absorption in the body. HH is not localized but a systemic disease; the manifestations of HH include cirrhosis, diabetes mellitus, cardiomyopathy, and pancreatitis. This case is about a 53-year-old female with a past medical history of heterozygous hereditary hemochromatosis who presents to the emergency department with abdominal pain, nausea, and vomiting and was found to have acute pancreatitis. This case report helps signify the importance of identifying and treating symptomatic heterozygous carriers of the HH gene mutation.

Screening for Hereditary Hemochromatosis in Newly Referred Diabetes Mellitus

Aims

Hereditary hemochromatosis (HH) is the most common inherited disease in European populations. It is particularly common in people of Irish heritage, approximately 2% of whom will be at risk of iron overload as a result of human homoeostatic iron regulator protein (HFE) gene mutations. We aimed to evaluate the utility of screening for HH in newly referred patients with DM of Irish heritage in a prospective study.

Methods

Of 575 patients newly referred between March 2018 and March 2021, 556 attended for blood testing, to include fasting transferrin saturations, prior to their first clinic visit. Patients with elevated transferrin saturations were further screened for hereditary hemochromatosis (HH) with HFE gene analysis.

Results

Transferrin saturations were elevated in 13 of 556 patients (2.3%), 3 of whom had a preexisting diagnosis of HH. Of the remaining 10 patients, 7 had HFE gene mutations suggestive of HH (2 C282Y homozygous, 3 C282Y/H63D compound heterozygous, and 2 H63D homozygous), 1 was a HH carrier (C282Y heterozygous), and 2 had normal genetics.

Conclusions

The prevalence of HH of 1.8% in this screened DM population is lower than the reported incidence of HH in the Irish population, suggesting a limited utility of routine screening for HH in newly referred patients with DM.

Targeting PKC alleviates iron overload in diabetes and hemochromatosis

Diabetes is one of the most prevalent chronic diseases worldwide. Iron overload increases the incidence of diabetes and aggravates diabetic complications that cause mortality. Reciprocally, diabetes potentially promotes body iron loading, but the mechanism remains not well understood. In this study, we demonstrated systemic iron excess and the upregulation of iron exporter ferroportin (Fpn) in the enterocytes and macrophages of multiple diabetic mouse models. Increased Fpn expression and iron efflux was also seen in the enterocytes of type 2 diabetic human patients. We further showed that protein kinase C (PKC), which is activated in hyperglycemia, was responsible for the sustained membrane expression of Fpn in physiological and in diabetic settings. For the first time, we identified that PKCs were novel binding proteins and positive regulators of Fpn. Mechanistically, hyperactive PKC promoted exocytotic membrane insertion while inhibited the endocytic trafficking of Fpn in the resting state. PKC also protected Fpn from internalization and degradation by its ligand hepcidin dependent on decreased ubiquitination and increased phosphorylation of Fpn. Importantly, the loss-of-function and pharmacological inhibition of PKC alleviated systemic iron overload in diabetes and hemochromatosis. Our study thus highlights PKC as a novel target in the control of systemic iron homeostasis.

Frequency Evaluation of the Interleukin-6 -174G>C Polymorphism and Homeostatic Iron Regulator (HFE) Mutations as Disease Modifiers in Patients Affected by Systemic Lupus Erythematosus and Rheumatoid Arthritis

Autoimmune diseases are generally characterized by a multifactorial etiology and are often associated with a genetic predisposition. Both iron metabolism and the inflammatory cytokine system have been shown to play a pivotal role in the dysregulation of the immune response in many different autoimmune conditions, rheumatologic diseases included. The purpose of this work was to analyze the frequency of mutations altering the expression of IL-6 or influencing iron metabolism in patients affected by autoimmune diseases such as Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE). In this study, 144 patients were enrolled: 77 and 67 patients were affected by RA and SLE, respectively. In these cohorts, the frequency of the IL-6 polymorphism -174G>C located in the IL-6 gene promoter was tested. Moreover, the frequencies of the three HFE gene variations associated with iron overload were analyzed: p.His63Asp, p.Ser65Cys and p.Cys282Tyr. The two mutations p.His63Asp and p.Ser65Cys in the HFE gene did not reach statistical significance in any of the comparisons, regardless of the statistical model, cohorts of patients and control populations analyzed. The frequencies of the p.Cys282Tyr mutation and the IL-6 polymorphism -174G>C were found to be overall significantly decreased in RA and SLE patients when the Dominant model and Allele contrast were adopted with both the Odds Ratio and Chi-square. Although further investigation is needed, the examination of the frequencies of the -174G>C IL-6 promoter polymorphism and HFE mutations may add some valuable information on the interplay linking iron metabolism, inflammation and immunity in autoimmune diseases such as SLE and RA.

Testing and Management of Iron Overload After Genetic Screening-Identified Hemochromatosis

Importance

HFE gene-associated hereditary hemochromatosis type 1 (HH1) is underdiagnosed, resulting in missed opportunities for preventing morbidity and mortality.

Objective

To assess whether screening for p.Cys282Tyr homozygosity is associated with recognition and management of asymptomatic iron overload.

Design, Setting, and Participants

This cross-sectional study obtained data from the Geisinger MyCode Community Health Initiative, a biobank of biological samples and linked electronic health record data from a rural, integrated health care system. Participants included those who received a p.Cys282Tyr homozygous result via genomic screening (MyCode identified), had previously diagnosed HH1 (clinically identified), and those negative for p.Cys282Tyr homozygosity between 2017 and 2018. Data were analyzed from April 2020 to August 2023.

Exposure

Disclosure of a p.Cys282Tyr homozygous result.

Main Outcomes and Measures

Postdisclosure management and HFE-associated phenotypes in MyCode-identified participants were analyzed. Rates of HFE-associated phenotypes in MyCode-identified participants were compared with those of clinically identified participants. Relevant laboratory values and rates of laboratory iron overload among participants negative for p.Cys282Tyr homozygosity were compared with those of MyCode-identified participants.

Results

A total of 86 601 participants had available exome sequences at the time of analysis, of whom 52 994 (61.4%) were assigned female at birth, and the median (IQR) age was 62.0 (47.0-73.0) years. HFE p.Cys282Tyr homozygosity was disclosed to 201 participants, of whom 57 (28.4%) had a prior clinical HH1 diagnosis, leaving 144 participants who learned of their status through screening. There were 86 300 individuals negative for p.Cys282Tyr homozygosity. After result disclosure, among MyCode-identified participants, 99 (68.8%) had a recommended laboratory test and 36 (69.2%) with laboratory or liver biopsy evidence of iron overload began phlebotomy or chelation. Fifty-three (36.8%) had iron overload; rates of laboratory iron overload were higher in MyCode-identified participants than participants negative for p.Cys282Tyr homozygosity (females: 34.1% vs 2.1%, P < .001; males: 39.0% vs 2.9%, P < .001). Iron overload (females: 34.1% vs 79.3%, P < .001; males: 40.7% vs 67.9%, P = .02) and some liver-associated phenotypes were observed at lower frequencies in MyCode-identified participants compared with clinically identified individuals.

Conclusions and Relevance

Results of this cross-sectional study showed the ability of genomic screening to identify undiagnosed iron overload and encourage relevant management, suggesting the potential benefit of population screening for HFE p.Cys282Tyr homozygosity. Further studies are needed to examine the implications of genomic screening for health outcomes and cost-effectiveness.

Hemochromatosis Genetic Variants and Musculoskeletal Outcomes: 11.5-Year Follow-Up in the UK Biobank Cohort Study

The iron overload disorder hemochromatosis is primarily caused by the homozygous HFE p.C282Y variant, but the scale of excess related musculoskeletal morbidity is uncertain. We estimated hemochromatosis-genotype associations with clinically diagnosed musculoskeletal outcomes and joint replacement surgeries in the UK Biobank community cohort. A total of 451,143 European ancestry participants (40 to 70 years at baseline) were followed in hospital records (mean 11.5-years). Cox proportional hazards models estimated HFE p.C282Y and p.H63D associations with incident outcomes. Male p.C282Y homozygotes (n = 1294) had increased incidence of osteoarthritis (n = 52, hazard ratio [HR]: 2.12 [95% confidence interval, CI: 1.61 to 2.80]; p = 8.8 × 10-8), hip replacement (n = 88, HR: 1.84 [95% CI: 1.49 to 2.27]; p = 1.6 × 10-8), knee replacement (n = 61, HR: 1.54 [95% CI: 1.20 to 1.98]; p = 8.4 × 10-4), and ankle and shoulder replacement, compared to males with no HFE mutations. Cumulative incidence analysis, using Kaplan-Meier lifetable probabilities demonstrated 10.4% of male homozygotes were projected to develop osteoarthritis and 15.5% to have hip replacements by age 75, versus 5.0% and 8.7% respectively without mutations. Male p.C282Y homozygotes also had increased incidence of femoral fractures (n = 15, HR: 1.72 [95% CI: 1.03 to 2.87]; p = 0.04) and osteoporosis (n = 21, HR: 1.71 [95% CI: 1.11 to 2.64]; p = 0.02), although the latter association was limited to those with liver fibrosis/cirrhosis diagnoses. Female p.C282Y homozygotes had increased incidence of osteoarthritis only (n = 57, HR: 1.46, [95% CI: 1.12 to 1.89]; p = 0.01). Male p.C282Y/p.H63D compound heterozygotes experienced a modest increased risk of hip replacements (n = 234, HR: 1.17 [95% CI: 1.02 to 1.33], p = 0.02), but this did not pass multiple testing corrections. In this large community cohort, the p.C282Y homozygote genotype was associated with substantial excess musculoskeletal morbidity in males. Wider HFE genotype testing may be justified, including in orthopedic clinics serving higher HFE variant prevalence populations. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Multivariate genome-wide analysis of aging-related traits identifies novel loci and new drug targets for healthy aging

The concept of aging is complex, including many related phenotypes such as healthspan, lifespan, extreme longevity, frailty and epigenetic aging, suggesting shared biological underpinnings; however, aging-related endpoints have been primarily assessed individually. Using data from these traits and multivariate genome-wide association study methods, we modeled their underlying genetic factor ('mvAge'). mvAge (effective n = ~1.9 million participants of European ancestry) identified 52 independent variants in 38 genomic loci. Twenty variants were novel (not reported in input genome-wide association studies). Transcriptomic imputation identified age-relevant genes, including VEGFA and PHB1. Drug-target Mendelian randomization with metformin target genes showed a beneficial impact on mvAge (P value = 8.41 × 10-5). Similarly, genetically proxied thiazolidinediones (P value = 3.50 × 10-10), proprotein convertase subtilisin/kexin 9 inhibition (P value = 1.62 × 10-6), angiopoietin-like protein 4, beta blockers and calcium channel blockers also had beneficial Mendelian randomization estimates. Extending the drug-target Mendelian randomization framework to 3,947 protein-coding genes prioritized 122 targets. Together, these findings will inform future studies aimed at improving healthy aging.

Iron, glucose and fat metabolism and obesity: an intertwined relationship

A bidirectional relationship exists between adipose tissue metabolism and iron regulation. Total body fat, fat distribution and exercise influence iron status and components of the iron-regulatory pathway, including hepcidin and erythroferrone. Conversely, whole body and tissue iron stores associate with fat mass and distribution and glucose and lipid metabolism in adipose tissue, liver, and muscle. Manipulation of the iron-regulatory proteins erythroferrone and erythropoietin affects glucose and lipid metabolism. Several lines of evidence suggest that iron accumulation and metabolism may play a role in the development of metabolic diseases including obesity, type 2 diabetes, hyperlipidaemia and non-alcoholic fatty liver disease. In this review we summarise the current understanding of the relationship between iron homoeostasis and metabolic disease.

Mendelian randomization study reveals a causal relationship between serum iron status and coronary heart disease and related cardiovascular diseases

Background

Growing observational studies have shown that abnormal systemic iron status is associated with Coronary heart disease (CHD). However, these results from observational studies was not entirely consistent.It remains unclear whether this relationship represents causality.It is necessary to explore the causal relationship between iron status and CHD and related cardiovascular diseases (CVD).

Objective

We aimed to investigate the potential casual relationship between serum iron status and CHD and related CVD using a two-sample Mendelian randomization (MR) approach.

Methods

Genetic statistics for single nucleotide polymorphisms (SNPs) between four iron status parameters were identified in a large-scale genome-wide association study (GWAS) conducted by the Iron Status Genetics organization. Three independent single nucleotide polymorphisms (SNPs) (rs1800562, rs1799945, and rs855791) aligned with four iron status biomarkers were used as instrumental variables. CHD and related CVD genetic statistics We used publicly available summary-level GWAS data. Five different MR methods random effects inverse variance weighting (IVW), MR Egger, weighted median, weighted mode, and Wald ratio were used to explore the causal relationship between serum iron status and CHD and related CVD.

Results

In the MR analysis, we found that the causal effect of serum iron (OR = 0.995, 95% CI = 0.992-0.998, p = 0.002) was negatively associated with the odds of coronary atherosclerosis (AS). Transferrin saturation (TS) (OR = 0.885, 95% CI = 0.797-0.982, p = 0.02) was negatively associated with the odds of Myocardial infarction (MI).

Conclusion

This MR analysis provides evidence for a causal relationship between whole-body iron status and CHD development. Our study suggests that a high iron status may be associated with a reduced risk of developing CHD.

The effect of systemic iron status on osteoarthritis: A mendelian randomization study

Objective: To assess the causal effect of systemic iron status by using four biomarkers (serum iron; transferrin saturation; ferritin; total iron-binding capacity) on knee osteoarthritis (OA), hip OA, total knee replacement, and total hip replacement using 2-sample Mendelian randomization (MR) design. Methods: Three instrument sets were used to construct the genetic instruments for the iron status: Liberal instruments (variants associated with one of the iron biomarkers), sensitivity instruments (liberal instruments exclude variants associated with potential confounders), and conservative instruments (variants associated with all four iron biomarkers). Summary-level data for four OA phenotypes, including knee OA, hip OA, total knee replacement, and total hip replacement were obtained from the largest genome-wide meta-analysis with 826,690 individuals. Inverse-variance weighted based on the random-effect model as the main approach was conducted. Weighted median, MR-Egger, and Mendelian randomization pleiotropy residual sum and outlier methods were used as sensitivity MR approaches. Results: Based on liberal instruments, genetically predicted serum iron and transferrin saturation were significantly associated with hip OA and total hip replacement, but not with knee OA and total knee replacement. Statistical evidence of heterogeneity across the MR estimates indicated that mutation rs1800562 was the SNP significantly associated with hip OA in serum iron (odds ratio, OR = 1.48), transferrin saturation (OR = 1.57), ferritin (OR = 2.24), and total-iron binding capacity (OR = 0.79), and hip replacement in serum iron (OR = 1.45), transferrin saturation (OR = 1.25), ferritin (OR = 1.37), and total-iron binding capacity (OR = 0.80). Conclusion: Our study suggests that high iron status might be a causal factor of hip OA and total hip replacement where rs1800562 is the main contributor.

European Association for Study of the Liver (EASL) clinical practice guidelines on haemochromatosis

The European Association for the Study of the Liver has recently updated guidance on haemochromatosis with a more extensive discussion on investigation and management.[ The new guidance focuses on non-invasive methods for fibrosis assessment and early diagnosis to include more extensive genetic testing if needed. Early diagnosis and treatment is vital as it reduces morbidity and mortality. We review this guideline and offer key updated messages with a focus on new developments since the last guidance and key aspects of current practice.

An observational and Mendelian randomisation study on iron status and sepsis

Iron deficiency is associated with a substantial burden of morbidity. However, supplementation of iron has been linked to increased rates of serious infection in randomised trials of children in sub-Saharan Africa. Randomised trials in other settings have been inconclusive and it is unknown if changes in levels of iron biomarkers are linked to sepsis in these other settings. We used genetic variants associated with levels of iron biomarkers as instrumental variables in a Mendelian randomisation (MR) analysis to test the hypothesis that increasing levels of iron biomarkers increase the risk of sepsis. In observational and MR analyses we found that increases in iron biomarkers increase the odds of sepsis. In stratified analyses, we show that this risk may be larger in those with iron deficiency and/or anaemia. Taken together, results here suggest a required caution in supplementation of iron and underline the role of iron homeostasis in severe infection.

Genetic modifiers of penetrance to liver endpoints in HFE hemochromatosis: Associations in a large community cohort

BACKGROUND

The iron overload condition hereditary hemochromatosis (HH) can cause liver cirrhosis and cancer, diabetes, and arthritis. Males homozygous for the p.C282Y missense mutation in the Homeostatin Iron Regulator (HFE) gene have greatest risk; yet, only a minority develop these conditions. We aimed to determine whether common genetic variants influencing iron levels or liver disease risk in the general population also modify clinical penetrance in HFE p.C282Y and p.H63D carriers.

METHODS

We studied 1294 male and 1596 female UK Biobank HFE p.C282Y homozygous participants of European ancestry with medical records up to 14 years after baseline assessment. Polygenic scores quantified genetic effects of blood iron biomarkers and relevant diseases (identified in the general population). Analyses were also performed in other HFE p.C282Y/p.H63D genotype groups.

RESULTS

In male p.C282Y homozygotes, a higher iron polygenic score increased the risk of liver fibrosis or cirrhosis diagnoses (odds ratio for the top 20% of iron polygenic score vs. the bottom 20% = 4.90: 95% confidence intervals, 1.63-14.73; p = 0.005), liver cancer, and osteoarthritis but not diabetes. A liver cirrhosis polygenic score was associated with liver cancer diagnoses. In female p.C282Y homozygotes, the osteoarthritis polygenic score was associated with increased osteoarthritis diagnoses and type-2 diabetes polygenic score with diabetes. However, the iron polygenic score was not robustly associated with diagnoses in p.C282Y female homozygotes or in other p.C282Y/p.H63D genotypes.

CONCLUSIONS

HFE p.C282Y homozygote penetrance to clinical disease in a large community cohort was partly explained by common genetic variants that influence iron and risks of related diagnoses in the general population, including polygenic scores in HH screening and diagnosis, may help in estimating prognosis and treatment planning.

Haemochromatosis revisited

Haemochromatosis is a genetic disease caused by hepcidin deficiency, responsible for an increase in intestinal iron absorption. Haemochromatosis is associated with homozygosity for the HFE p.Cys282Tyr mutation. However, rare cases of haemochromatosis (non-HFE haemochromatosis) can also be caused by pathogenic variants in other genes (such as HJV, HAMP, TFR2 and SLC40A1). A working group of the International Society for the Study of Iron in Biology and Medicine (BIOIRON Society) has concluded that the classification based in different molecular subtypes is difficult to be adopted in clinical practice and has proposed a new classification approaching clinical questions and molecular complexity. The aim of the present review is to provide an update on classification, pathophysiology and therapeutic recommendations.

Patient-reported outcomes and their relation with iron parameters in HFE haemochromatosis during maintenance therapy: A prospective cohort study

BACKGROUND & AIMS

The standard of care for haemochromatosis is regular phlebotomy in order to maintain low ferritin levels. Many patients report fatigue or joint pain despite serum ferritin within the therapeutic targets. We evaluated Patient-Reported Outcomes, and their relation with iron parameters, in C282Y homozygous patients undergoing maintenance phlebotomy.

METHODS

Patients were prospectively enrolled in a French referral care centre. At each phlebotomy, patients completed a numeric fatigue scale, a joint pain questionnaire and SF-36 Mental Component Score (MCS) and Physical Component Score (PCS). Haemoglobin, iron, TS and ferritin were collected concomitantly.

RESULTS

About 701 visits were performed in 259 patients. The median fatigue score was 3/10; 171 (66%) patients reported joint pain. Age and worsening of joint pain were associated with fatigue (p < .0001 for both). Female gender (p < .037), age (p < .003), and a decrease of TS (p = .050) were associated with joint pain. Main features associated with PCS <50 were worsening of joint pain and age (p < .001 for both) and TS <20% (p < .02).

CONCLUSIONS

Fatigue was independent from iron parameters. The main factor impacting quality of life was joint pain, which was more severe in patients with low TS values. Then, a more precise monitoring of TS should be proposed during haemochromatosis maintenance therapy; while less stringent monitoring of serum ferritin levels could be tested.

Severe osteoporosis as atypical presentation of hereditary hemochromatosis

Besides important metabolic repercussions, iron overload is reported to be associated with deleterious effects on articulations and bones. We present the case of a male patient diagnosed with severe osteoporosis and vertebral fracture, in whom the evaluation for secondary osteoporosis revealed hereditary hemochromatosis.

Twenty-Five Years of Contemplating Genotype-Based Hereditary Hemochromatosis Population Screening

Hereditary hemochromatosis (HH) is a rather frequent, preventable disease because the progressive iron overload affecting many organs can be effectively reduced by phlebotomy. Even before the discovery of the major gene, HFE, in 1996, hemochromatosis was seen as a candidate for population-wide screening programmes. A US Centers of Disease Control and the National Human Genome Research Institute expert panel convened in 1997 to consider genotype-based HH population-wide screening and decided that the scientific evidence available at that time was insufficient and advised against. In spite of a large number of studies performed within the last 25 years, addressing all aspects of HH natural history, health economics, and social acceptability, no professional body worldwide has reverted this decision, and HH remains a life-threatening condition that often goes undetected at a curable stage.

Hereditary Hemochromatosis Variant Associations with Incident Nonliver Malignancies: 11-Year Follow-up in UK Biobank

BACKGROUND

In European ancestry populations, iron overload disorder hereditary hemochromatosis is predominantly caused by HFE p.C282Y and p.H63D mutations. Male p.C282Y homozygotes have markedly increased hepatic malignancy incidence, but risks for other cancers in male and female homozygotes are unclear.

METHODS

451,143 UK Biobank European ancestry participants (aged 40-70 years; 54.3% female) were followed (mean 11.6 years) via hospital admissions and national cancer registries. We estimated risks of any incident cancer (other than nonmelanoma and liver cancer) and common incident cancers [bladder, blood (with subanalyses of leukemia and lymphoma), bone, brain, breast, colorectal, kidney, lung, melanoma, esophageal, ovarian, pancreatic, prostate and stomach] in those with p.C282Y and p.H63D genotypes, compared with participants without HFE mutations.

RESULTS

Male p.C282Y homozygotes (n = 2,890, 12.1% with baseline diagnosed hereditary hemochromatosis) had increased incidence of prostate cancer [6.8% vs. 5.4% without mutations; HR = 1.32; 95% confidence interval (CI), 1.07-1.63; P = 0.01; Bonferroni adjusted P = 0.17] during follow-up. In life table estimates from ages 40 to 75 years, 14.4% of male p.C282Y homozygotes are projected to develop prostate cancer (versus 10.7% without mutations, excess 3.8%; 95% CI, 1.3-6.8). No increases in risks were found for other studied cancers in male or female p.C282Y homozygotes, or in any other p.C282Y/p.H63D genotype groups of either sex.

CONCLUSIONS

In a large community sample of male p.C282Y homozygotes, there is suggestive evidence of increased prostate cancer incidence, with no evidence of excess of other studied (nonliver) cancers.

IMPACT

Replication of results in other large community genotyped cohorts are needed to confirm if clinical monitoring for prostate cancer is necessary in p.C282Y homozygous males.

Association of Genetic Variant Linked to Hemochromatosis With Brain Magnetic Resonance Imaging Measures of Iron and Movement Disorders

Importance

Hereditary hemochromatosis (HH) is an autosomal recessive genetic disorder that leads to iron overload. Conflicting results from previous research has led some to believe the brain is spared the toxic effects of iron in HH.

Objective

To test the association of the strongest genetic risk variant for HH on brainwide measures sensitive to iron deposition and the rates of movement disorders in a substantially larger sample than previous studies of its kind.

Design, Setting, and Participants

This cross-sectional retrospective study included participants from the UK Biobank, a population-based sample. Genotype, health record, and neuroimaging data were collected from January 2006 to May 2021. Data analysis was conducted from January 2021 to April 2022. Disorders tested included movement disorders (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision [ICD-10], codes G20-G26), abnormalities of gait and mobility (ICD-10 codes R26), and other disorders of the nervous system (ICD-10 codes G90-G99).

Exposures

Homozygosity for p.C282Y, the largest known genetic risk factor for HH.

Main Outcomes and Measures

T2-weighted and T2* signal intensity from brain magnetic resonance imaging scans, measures sensitive to iron deposition, and clinical diagnosis of neurological disorders.

Results

The total cohort consisted of 488 288 individuals (264 719 female; ages 49-87 years, largely northern European ancestry), 2889 of whom were p.C282Y homozygotes. The neuroimaging analysis consisted of 836 individuals: 165 p.C282Y homozygotes (99 female) and 671 matched controls (399 female). A total of 206 individuals were excluded from analysis due to withdrawal of consent. Neuroimaging analysis showed that p.C282Y homozygosity was associated with decreased T2-weighted and T2* signal intensity in subcortical motor structures (basal ganglia, thalamus, red nucleus, and cerebellum; Cohen d >1) consistent with substantial iron deposition. Across the whole UK Biobank (2889 p.C282Y homozygotes, 485 399 controls), we found a significantly increased prevalence for movement disorders in male homozygotes (OR, 1.80; 95% CI, 1.28-2.55; P = .001) but not female individuals (OR, 1.09; 95% CI, 0.70-1.73; P = .69). Among the 31 p.C282Y male homozygotes with a movement disorder, only 10 had a concurrent HH diagnosis.

Conclusions and Relevance

These findings indicate increased iron deposition in subcortical motor circuits in p.C282Y homozygotes and confirm an increased association with movement disorders in male homozygotes. Early treatment in HH effectively prevents the negative consequences of iron overload in the liver and heart. Our work suggests that screening for p.C282Y homozygosity in high-risk individuals also has the potential to reduce brain iron accumulation and to reduce the risk of movement disorders among male individuals who are homozygous for this mutation.

New Horizons: the value of UK Biobank to research on endocrine and metabolic disorders

UK Biobank is an intensively characterized prospective study of 500 000 men and women, aged 40 to 69 years when recruited, between 2006 and 2010, from the general population of the United Kingdom. Established as an open-access resource for researchers worldwide to perform health research that is in the public interest, UK Biobank has collected (and continues to collect) a vast amount of data on genetic, physiological, lifestyle, and environmental factors, with prolonged follow-up of heath conditions through linkage to administrative electronic health records. The study has already demonstrated its unique value in enabling research into the determinants of common endocrine and metabolic diseases. The importance of UK Biobank, heralded as a flagship project for UK health research, will only increase over time as the number of incident disease events accrue, and the study is enhanced with additional data from blood assays (such as whole-genome sequencing, metabolomics, and proteomics), wearable technologies (including physical activity and cardiac monitors), and body imaging (magnetic resonance imaging and dual-energy X-ray absorptiometry). This unique research resource is likely to transform our understanding of the causes, diagnosis, and treatment of many endocrine and metabolic disorders.

EASL Clinical Practice Guidelines on haemochromatosis

Haemochromatosis is characterised by elevated transferrin saturation (TSAT) and progressive iron loading that mainly affects the liver. Early diagnosis and treatment by phlebotomy can prevent cirrhosis, hepatocellular carcinoma, diabetes, arthropathy and other complications. In patients homozygous for p.Cys282Tyr in HFE, provisional iron overload based on serum iron parameters (TSAT >45% and ferritin >200 μg/L in females and TSAT >50% and ferritin >300 μg/L in males and postmenopausal women) is sufficient to diagnose haemochromatosis. In patients with high TSAT and elevated ferritin but other HFE genotypes, diagnosis requires the presence of hepatic iron overload on MRI or liver biopsy. The stage of liver fibrosis and other end-organ damage should be carefully assessed at diagnosis because they determine disease management. Patients with advanced fibrosis should be included in a screening programme for hepatocellular carcinoma. Treatment targets for phlebotomy are ferritin <50 μg/L during the induction phase and <100 μg/L during the maintenance phase.

Incomplete Penetrance and Variable Expressivity: From Clinical Studies to Population Cohorts

The same genetic variant found in different individuals can cause a range of diverse phenotypes, from no discernible clinical phenotype to severe disease, even among related individuals. Such variants can be said to display incomplete penetrance, a binary phenomenon where the genotype either causes the expected clinical phenotype or it does not, or they can be said to display variable expressivity, in which the same genotype can cause a wide range of clinical symptoms across a spectrum. Both incomplete penetrance and variable expressivity are thought to be caused by a range of factors, including common variants, variants in regulatory regions, epigenetics, environmental factors, and lifestyle. Many thousands of genetic variants have been identified as the cause of monogenic disorders, mostly determined through small clinical studies, and thus, the penetrance and expressivity of these variants may be overestimated when compared to their effect on the general population. With the wealth of population cohort data currently available, the penetrance and expressivity of such genetic variants can be investigated across a much wider contingent, potentially helping to reclassify variants that were previously thought to be completely penetrant. Research into the penetrance and expressivity of such genetic variants is important for clinical classification, both for determining causative mechanisms of disease in the affected population and for providing accurate risk information through genetic counseling. A genotype-based definition of the causes of rare diseases incorporating information from population cohorts and clinical studies is critical for our understanding of incomplete penetrance and variable expressivity. This review examines our current knowledge of the penetrance and expressivity of genetic variants in rare disease and across populations, as well as looking into the potential causes of the variation seen, including genetic modifiers, mosaicism, and polygenic factors, among others. We also considered the challenges that come with investigating penetrance and expressivity.