Iron-overload-related disease in HFE hereditary hemochromatosis

Haemochromatosis Genotypes and Incident Dementia in a Prospective Study of Older Adults

BACKGROUND AND OBJECTIVES

Variants in the homeostatic iron regulator (HFE) gene are prevalent among individuals of European ancestry and have been linked to an increased risk of dementia. This study aimed to evaluate the effects of HFE p.Cys282Tyr and p.His63Asp variants on serum ferritin levels and the incidence of dementia in a cohort of initially healthy older adults.

METHOD

This prospective longitudinal study used data from the Aspirin in Reducing Events in the Elderly trial. Participants had no history of cardiovascular disease, dementia, or cognitive decline at enrollment. Genotyping for HFE p.Cys282Tyr and p.His63Asp variants was conducted using microarrays, and baseline serum ferritin concentrations were measured in peripheral blood samples. Dementia diagnoses were confirmed by an adjudication committee over a median follow-up of 6.4 years. Associations were evaluated using Cox proportional hazards models adjusted for related covariates.

RESULTS

The study included 12,174 unrelated, healthy participants of European ancestry aged 70 years or older, comprising 5,583 men (45.9%) and 6,591 women (54.1%). The median age was 73.7 years (interquartile range [IQR]: 71.6-76.9) for men and 73.9 years (IQR: 71.7-77.5) for women. Compared with the wild-type group, men with p.Cys282Tyr+/+ (p = 0.048) and p.Cys282Tyr+/p.His63Asp + genotypes (p < 0.001) had significantly higher baseline ferritin levels. Women with p.His63Asp+/+ (p = 0.015) and p.Cys282Tyr+/p.His63Asp+ (p < 0.001) genotypes also exhibited elevated ferritin levels. No significant association was observed between baseline serum ferritin levels and dementia risk. However, men with p.His63Asp+/+ genotype had a significantly higher risk of incident dementia (adjusted hazard ratio = 2.39, 95% CI 1.25-4.57, p = 0.009) compared with those without HFE variations. This association was not observed in women.

DISCUSSION

Among initially healthy older adults, HFE p.His63Asp homozygosity was associated with a higher risk of incident dementia in men but not women. These findings highlight a potential sex-specific genetic risk factor for dementia and warrant further research into the underlying mechanisms linking p.His63Asp and dementia.

Choosing Wisely Canada recommendations for clinical biochemistry: test ordering for sustainable and high-quality patient care

Laboratory Medicine is growing at a rapid rate in both the breadth of unique tests and the total number of tests performed per year. Inappropriate overutilization of laboratory tests can lead to patient harm, excessive environmental waste and increased carbon emissions. A focus on reducing inefficiencies in healthcare is needed to ensure a robust and sustainable healthcare system. To promote laboratory sustainability, the Canadian Society of Clinical Chemists (CSCC) has developed ten recommendations related to medical tests within clinical biochemistry. These recommendations are designed as 'low-hanging fruit' that should be adopted by both hospital and community laboratories. By implementing automated strategies and/or educational approaches to reduce misuse of laboratory resources, clinical laboratories can move toward a more sustainable model that improves patient care. This list of recommendations, created for Choosing Wisely Canada, covers tests for diabetes, celiac disease, monoclonal gammopathies, iron disorders, liver disorders, kidney disorders, substance use disorders, and allergen testing.

Risk profiling for cirrhosis and hepatocellular carcinoma in HFE hemochromatosis using mobilizable iron stores and alcohol consumption

HFE hemochromatosis (HH) may cause cirrhosis and hepatocellular carcinoma (HCC). Progression to these endpoints depends on the severity of iron overload and cofactors, such as alcohol. We evaluated alcohol and iron-related risk factors in relation to cirrhosis at diagnosis and future development of HCC in a retrospective analysis of 197 HH subjects. The proportion of subjects either with cirrhosis or who developed HCC during follow-up were 29/197 (14.7%) or 10/197 (5.1%), respectively. The median (IQR) follow-up time after diagnosis was 15.2 (4.6 to 22.1) years. The median mobilizable iron stores and daily alcohol consumption (IQR) were 6.0 (3.8-11.0) g and 20 (0-40) g, respectively. An optimal logistic regression model for the odds of cirrhosis was developed by adding candidate liver insult variables (mobilizable iron, alcohol consumption, and age as a surrogate for duration of exposure) in a forward stepwise strategy using area under the receiver operating characteristic curve (AUROC) analysis and the corrected Akaike information criterion. This model demonstrated an AUROC (95% CI) of 0.966 (0.935-0.996), with sensitivity 76 (58-88)% and specificity 97 (93-99) % for prediction of cirrhosis and had a negative predictive value of 99.4 (95% CI 96.7-99.97) % for development of HCC. Thus, future risk of HCC can be assessed from mobilizable iron stores and alcohol consumption of HH subjects.

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.

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.

Hypoparathyroidism in adults with iron overload diseases (IOD): evidence of a subclinical phenotype

PURPOSE

To explore the prevalence of hypoparathyroidism (HPT), overt and subclinical, in a cohort of adults with Iron Overload Diseases (IOD). Secondary aim was to test the calcium (Ca)-to-phosphorus (P) ratio performance in identifying HPT.

METHODS

Single-center, prospective, case-control study. Sixty-five IOD, 40 with thalassemia major/intermedia (TMI) and 25 with hemochromatosis (HC), and 76 age-matched controls were included. Main outcomes (serum Ca, P, Ca/P ratio, intact parathyroid hormone (PTH), albumin) defined overt and subclinical HPT.

RESULTS

Albumin-adjusted Ca was lower (p = 0.004) and P higher (p = 0.002) comparing IOD to controls. Ca/P ratio was lower in IOD than controls (p < 0.001); PTH did not change. P was higher and Ca/P lower comparing TMI to HC and controls (p < 0.001); Ca did not change. A total of 28/65 IOD (43%) had HPT (9.2% overt, 33.8% subclinical) whose prevalence was higher in TMI than HC (p < 0.001). Ca/P ratio <2.32 had sensitivity 71.4% and specificity 83.9% in detecting overt/subclinical HPT. IOD with Ca/P ratio <2.32 (1.78 in SI) had an almost 12-fold increased likelihood to be affected by HPT (OR 12.92 [3.90-42.82]; p < 0.001). Ca/P (p = 0.002) was the only independent risk factor for HPT at multivariate analysis.

CONCLUSIONS

HPT, especially non-classical subclinical HPT, is common in adult IOD with higher prevalence in TMI than HC. Ca/P ratio <2.32 is accurate to screen for overt/subclinical HPT and should be periodically evaluated in IOD to early detect an unbalanced mineral metabolism, and to monitor a possible evolution from subclinical to overt HPT.

Influence of Sex in the Development of Liver Diseases

The liver is a sexually dimorphic organ. Sex differences in prevalence, progression, prognosis, and treatment prevail in most liver diseases, and the mechanism of how liver diseases act differently among male versus female patients has not been fully elucidated. Biological sex differences in normal physiology and disease arise principally from sex hormones and/or sex chromosomes. Sex hormones contribute to the development and progression of most liver diseases, with estrogen- and androgen-mediated signaling pathways mechanistically involved. In addition, genetic factors in sex chromosomes have recently been found to contribute to the sex disparity of many liver diseases, which might explain, to some extent, the difference in gene expression pattern, immune response, and xenobiotic metabolism between men and women. Although increasing evidence suggests that sex is one of the most important modulators of disease prevalence and outcomes, at present, basic and clinical studies have long been sex unbalanced, with female subjects underestimated. As such, this review focuses on sex disparities of liver diseases and summarizes the current understanding of sex-specific mechanisms, including sex hormones, sex chromosomes, etc. We anticipate that understanding sex-specific pathogenesis will aid in promoting personalized therapies for liver disease among male versus female patients.

Impact of body fat composition on liver iron overload severity in hemochromatosis: a retrospective MRI analysis

PURPOSE

To evaluate the correlation between ectopic adipose tissue and iron overload severity in patients with hemochromatosis.

MATERIAL AND METHODS

A retrospective cohort of 52 patients who underwent liver iron concentration quantification from January 2015 to October 2023 using a 3.0T MRI scanner. R2* relaxation times and proton density fat fraction (PDFF) were assessed for the entire liver volume and a specific region of interest (ROI) placed in the right lobe. Total body fat (TF), subcutaneous fat (SCF), intermuscular fat (IMF), and visceral fat (VSF) percentages were calculated from a single axial slice at the level of the third lumbar vertebra. Additionally, ratios of IMF-to-VSF, IMF-to-SCF, and SCF-to-VSF were calculated. Standard iron laboratory parameters were collected at least one month prior to MRI. Pearson correlation coefficient was used for correlation analysis.

RESULTS

The mean age of participants was 53.9 ± 19.6 years. IMF positively correlated with R2* values in the ROI (p = 0.005, rs = 0.382) and entire liver (p = 0.016, rs = 0.332). Conversely, VSF negatively correlated with R2* values from the ROI (p = < 0.001, rs = - 0.488) and entire liver (p = < 0.001, rs = - 0.459). Positive correlations were also found between IMF-to-VSF and R2* of the ROI (p = 0.003, rs = 0.400) and whole liver (p = 0.008, rs = 0.364). Ferritin levels positively correlated with R2* values calculated from ROI (p = 0.002, rs = 0.417) and whole liver volume (p = 0.004, rs = 0.397). A positive correlation was noted between PDFF of the entire liver and TF (p = 0.024, rs = 0.313).

CONCLUSION

The percentage of Intermuscular and visceral adipose tissues correlates with the severity of liver iron overload in hemochromatosis patients.

Factors related to mean corpuscular volume in HFE p.C282Y homozygotes

Introduction

The aim of this study was to define the relationships between factors other than transferrin saturation (TS) to mean corpuscular volume (MCV) and macrocytosis (MCV > 100 fL) in HFE p.C282Y (rs1800562) homozygotes.

Methods

We studied white post-screening participants with p.C282Y homozygosity who did not have anemia, report cirrhosis or pregnancy, or use medications that increase MCV. We analyzed relations of MCV and macrocytosis with age, sex, diabetes reports, daily alcohol consumption, swollen or tender 2nd/3rd metacarpophalangeal (MCP) joints, TS, and serum ferritin (SF).

Results

There were 257 participants (110 men and 147 women). Median alcohol consumption, median TS, median SF, and macrocytosis prevalence were significantly greater in men. Relative risk of macrocytosis in men was 2.81. In men and women, there were significant positive Pearson's correlations of MCV versus age and Spearman's correlations of MCV versus alcohol consumption and TS. Mean MCV and macrocytosis prevalence were significantly greater in participants with than without swollen or tender 2nd/3rd MCP joints. Linear regression on MCV revealed positive associations: age (p < 0.0001), alcohol consumption (p = 0.0007), and TS (p < 0.0001). Logistic regression on macrocytosis revealed an odds ratio for age of 1.04 (95% confidence interval: 1.00, 1.07).

Conclusions

MCV in HFE p.C282Y homozygotes is positively related to age, daily alcohol consumption, TS, and swollen or tender 2nd/3rd MCP joints.

Hemochromatosis

Hemochromatosis is an inheritable condition that mainly affects White populations of European descent. Most patients remain asymptomatic, but others develop advanced organ damage that reduces quality of life and long-term survival. Arthropathy, diabetes mellitus, cirrhosis, hypogonadotropic hypogonadism, and cardiomyopathy are key clinical manifestations. Primary care and hospital medicine physicians play an essential role in early identification of this disease, which can be accomplished via standard hematologic testing. Early diagnosis and therapeutic phlebotomy improve clinical outcomes.

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.

Hereditary haemochromatosis: A review

Hereditary haemochromatosis (HH) is the commonest genetic condition among populations of Northern European ancestry. Mutations to the HFE gene leads to uninhibited intestinal iron absorption followed by excess iron deposition in various organs such as the liver, pituitary gland, pancreas and heart. Due to variable biochemical and clinical penetrance, not all individuals with C282Y homozygosity will develop HH. Early diagnosis is crucial to prevent morbidity and mortality but is challenging with most patients not exhibiting any symptoms. Patients with HH should undergo clinical assessment to evaluate their symptoms, presence of organ damage and hepatic fibrosis using transient elastography. Patients who are negative for the HFE mutations but have significant liver iron loading seen on magnetic resonance imaging should be reviewed by a specialist and considered for genetic tests looking for the rarer non-HFE mutations. HH patients are predominantly treated with venesection which can improve symptoms, hepatic fibrosis and mortality.

The dual loss and gain of function of the FPN1 iron exporter results in the ferroportin disease phenotype

Heterozygous mutations in SLC40A1, encoding a multi-pass membrane protein of the major facilitator superfamily known as ferroportin 1 (FPN1), are responsible for two distinct hereditary iron-overload diseases: ferroportin disease, which is associated with reduced FPN1 activity (i.e., decrease in cellular iron export), and SLC40A1-related hemochromatosis, which is associated with abnormally high FPN1 activity (i.e., resistance to hepcidin). Here, we report three SLC40A1 missense variants with opposite functional consequences. In cultured cells, the p.Arg40Gln and p.Ser47Phe substitutions partially reduced the ability of FPN1 to export iron and also partially reduced its sensitivity to hepcidin. The p.Ala350Val substitution had more profound effects, resulting in low FPN1 iron egress and weak FPN1/hepcidin interaction. Structural analyses helped to differentiate the first two substitutions, which are predicted to cause local instabilities, and the third, which is thought to prevent critical rigid-body movements that are essential to the iron transport cycle. The phenotypic traits observed in a total of 12 affected individuals are highly suggestive of ferroportin disease. Our findings dismantle the classical dualism of FPN1 loss versus gain of function, highlight some specific and unexpected functions of FPN1 transmembrane helices in the molecular mechanism of iron export and its regulation by hepcidin, and extend the spectrum of rare genetic variants that may cause ferroportin disease.

Sex similarities and divergences in systemic and muscle iron metabolism adaptations to extreme physical inactivity in rats

BACKGROUND

Previous data in humans suggest that extreme physical inactivity (EPI) affects iron metabolism differently between sexes. Our objective was to deepen the underlying mechanisms by studying rats of both sexes exposed to hindlimb unloading (HU), the reference experimental model mimicking EPI.

METHODS

Eight-week-old male and female Wistar rats were assigned to control (CTL) or hindlimb unloading (HU) conditions (n = 12/group). After 7 days of HU, serum, liver, spleen, and soleus muscle were removed. Iron parameters were measured in serum samples, and ICP-MS was used to quantify iron in tissues. Iron metabolism genes and proteins were analysed by RT-qPCR and Western blot.

RESULTS

Compared with control males, control females exhibited higher iron concentrations in serum (+43.3%, p < 0.001), liver (LIC; +198%, P < 0.001), spleen (SIC; +76.1%, P < 0.001), and transferrin saturation (TS) in serum (+53.3%, P < 0.001), contrasting with previous observations in humans. HU rat males, but not females, exhibited an increase of LIC (+54% P < 0.001) and SIC (+30.1%, P = 0.023), along with a rise of H-ferritin protein levels (+60.9% and +134%, respectively, in liver and spleen; P < 0.05) and a decrease of TFRC protein levels (-36%; -50%, respectively, P < 0.05). HU males also exhibited an increase of splenic HO-1 and NRF2 mRNA levels, (p < 0.001), as well as HU females (P < 0.001). Concomitantly to muscle atrophy observed in HU animals, the iron concentration increased in soleus in females (+26.7, P = 0.004) while only a trend is observed in males (+17.5%, P = 0.088). In addition, the H-ferritin and myoglobin protein levels in soleus were increased in males (+748%, P < 0.001, +22%, P = 0.011, respectively) and in females (+369%, P < 0.001, +21.9%, P = 0.007, respectively), whereas TFRC and ferroportin (FPN) protein levels were reduced in males (-68.9%, P < 0.001, -76.8%, P < 0.001, respectively) and females (-75.9%, P < 0.001, -62.9%, P < 0.001, respectively). Interestingly, in both sexes, heme exporter FLVCR1 mRNA increased in soleus, while protein levels decreased (-39.9% for males P = 0.010 and -49.1% for females P < 0.001).

CONCLUSIONS

Taken together, these data support that, in rats (1) extreme physical inactivity differently impacts the distribution of iron in both sexes, (2) splenic erythrophagocytosis could play a role in this iron misdistribution. The higher iron concentrations in atrophied soleus from both sexes are associated with a decoupling between the increase in iron storage proteins (i.e., ferritin and myoglobin) and the decrease in levels of iron export proteins (i.e., FPN and FLVCR1), thus supporting an iron sequestration in skeletal muscle under extreme physical inactivity.

Fatigue Assessment in Patients with Hereditary Hemochromatosis: First Use of the Popular Diagnostic Tools

Background: Hereditary hemochromatosis (HH) is a genetic condition with fatigue as an essential but not precisely assessed symptom. While some well-specified scales for fatigue assessment in some pathologies exist, data on their usefulness in HH need to be collected. This research aimed to evaluate fatigue in HH using the Fatigue Assessment Scale (FAS), Fatigue Severity Scale (FSS), and Chalder Fatigue Scale (CFQ). Methodology: Seventy-nine HH patients underwent a questionnaire containing items about detailed medical history and the FAS, FSS, and CFQ scales. Twenty-five sex- and age-matched healthy persons constituted the control group (controls); additionally, thirty blood donors (donors) were compared. Results: The fatigue indices were significantly worse in the HH patients than in the controls and donors (HH vs. controls p-value: FAS = 0.003, FSS < 0.001, and CFQ = 0.003; HH vs. donors p-value: FAS = 0.025, FSS < 0.001, and CFQ = 0.041). There were no differences between the severity of fatigue and the specific genotype or the age of the patients. The HH women presented more severe fatigue than the men. High internal consistency and reliability for each scale were revealed: the Cronbach alpha values were as follows: FAS 0.92, FSS 0.95, and CFQ 0.93. Additionally, the construct validity and factorial validity of the implemented scales were confirmed. Conclusions: The HH patients exhibited significantly worse fatigue across all the scales. The FAS, FSS, and CFQ are simple and reliable diagnostic tools for assessing and quantifying fatigue for clinical and research purposes.

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.

The endosymbiont Spiroplasma poulsonii increases Drosophila melanogaster resistance to pathogens by enhancing iron sequestration and melanization

Facultative endosymbiotic bacteria, such as Wolbachia and Spiroplasma species, are commonly found in association with insects and can dramatically alter their host physiology. Many endosymbionts are defensive and protect their hosts against parasites or pathogens. Despite the widespread nature of defensive insect symbioses and their importance for the ecology and evolution of insects, the mechanisms of symbiont-mediated host protection remain poorly characterized. Here, we utilized the fruit fly Drosophila melanogaster and its facultative endosymbiont Spiroplasma poulsonii to characterize the mechanisms underlying symbiont-mediated host protection against bacterial and fungal pathogens. Our results indicate a variable effect of S. poulsonii on infection outcome, with endosymbiont-harboring flies being more resistant to Rhyzopus oryzae, Staphylococcus aureus, and Providencia alcalifaciens but more sensitive or as sensitive as endosymbiont-free flies to the infections with Pseudomonas species. Further focusing on the protective effect, we identified Transferrin-mediated iron sequestration induced by Spiroplasma as being crucial for the defense against R. oryzae and P. alcalifaciens. In the case of S. aureus, enhanced melanization in Spiroplasma-harboring flies plays a major role in protection. Both iron sequestration and melanization induced by Spiroplasma require the host immune sensor protease Persephone, suggesting a role of proteases secreted by the symbiont in the activation of host defense reactions. Hence, our work reveals a broader defensive range of Spiroplasma than previously appreciated and adds nutritional immunity and melanization to the defensive arsenal of symbionts.

IMPORTANCE

Defensive endosymbiotic bacteria conferring protection to their hosts against parasites and pathogens are widespread in insect populations. However, the mechanisms by which most symbionts confer protection are not fully understood. Here, we studied the mechanisms of protection against bacterial and fungal pathogens mediated by the Drosophila melanogaster endosymbiont Spiroplasma poulsonii. We demonstrate that besides the previously described protection against wasps and nematodes, Spiroplasma also confers increased resistance to pathogenic bacteria and fungi. We identified Spiroplasma-induced iron sequestration and melanization as key defense mechanisms. Our work broadens the known defense spectrum of Spiroplasma and reveals a previously unappreciated role of melanization and iron sequestration in endosymbiont-mediated host protection. We propose that the mechanisms we have identified here may be of broader significance and could apply to other endosymbionts, particularly to Wolbachia, and potentially explain their protective properties.

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.

Cardiomyocyte-specific overexpression of FPN1 diminishes cardiac hypertrophy induced by chronic intermittent hypoxia

The significance of iron in myocardial mitochondria function cannot be underestimated, because deviations in iron levels within cardiomyocytes may have profound detrimental effects on cardiac function. In this study, we investigated the effects of ferroportin 1 (FPN1) on cardiac iron levels and pathological alterations in mice subjected to chronic intermittent hypoxia (CIH). The cTNT-FPN1 plasmid was administered via tail vein injection to induce the mouse with FPN1 overexpression in the cardiomyocytes. CIH was established by exposing the mice to cycles of 21%-5% FiO2 for 3 min, 8 h per day. Subsequently, the introduction of hepcidin resulted in a reduction in FPN1 expression, and H9C2 cells were used to establish an IH model to further elucidate the role of FPN1. First, FPN1 overexpression ameliorated CIH-induced cardiac dysfunction, myocardial hypertrophy, mitochondrial damage and apoptosis. Second, FPN1 overexpression attenuated ROS levels during CIH. In addition, FPN1 overexpression mitigated CIH-induced cardiac iron accumulation. Moreover, the administration of hepcidin resulted in a reduction in FPN1 levels, further accelerating the CIH-induced levels of ROS, LIP and apoptosis in H9C2 cells. These findings indicate that the overexpression of FPN1 in cardiomyocytes inhibits CIH-induced cardiac iron accumulation, subsequently reducing ROS levels and mitigating mitochondrial damage. Conversely, the administration of hepcidin suppressed FPN1 expression and worsened cardiomyocyte iron toxicity injury.

Hemochromatosis-How Not to Overlook and Properly Manage "Iron People"-A Review

Hemochromatosis (HC) is the main genetic disorder of iron overload and is regarded as metal-related human toxicosis. HC may result from HFE and rare non-HFE gene mutations, causing hepcidin deficiency or, sporadically, hepcidin resistance. This review focuses on HFE-related HC. The illness presents a strong biochemical penetrance, but its prevalence is low. Unfortunately, the majority of patients with HC remain undiagnosed at their disease-curable stage. The main aim of HC management is to prevent iron overload in its early phase and remove excess iron from the body by phlebotomy in its late stage. Raising global awareness of HC among health staff, teaching them how not to overlook early HC manifestations, and paying attention to careful patient monitoring remain critical management strategies for preventing treatment delays, upgrading its efficacy, and improving patient prognosis.

Minimizing Contact Resistance and Flicker Noise in Micro Graphene Hall Sensors Using Persistent Carbene Modified Gold Electrodes

Scalable micro graphene Hall sensors (μGHSs) hold tremendous potential for highly sensitive and label-free biomagnetic sensing in physiological solutions. To enhance the performance of these devices, it is crucial to optimize frequency-dependent flicker noise to reduce the limit of detection (LOD), but it remains a great challenge due to the large contact resistance at the graphene-metal contact. Here we present a surface modification strategy employing persistent carbene on gold electrodes to reduce the contact resistivity by a factor of 25, greatly diminishing μGHS flicker noise by a factor of 1000 to 3.13 × 10-14 V2/Hz while simultaneously lowering the magnetic LOD SB1/2 to 1440 nT/Hz1/2 at 1 kHz under a 100 μA bias current. To the best of our knowledge, this represents the lowest SB1/2 reported for scalable μGHSs fabricated through wafer-scale photolithography. The reduction in contact noise is attributed to the π-π stacking interaction between the graphene and the benzene rings of persistent carbene, as well as the decrease in the work function of gold as confirmed by Kelvin Probe Force Microscopy. By incorporating a microcoil into the μGHS, we have demonstrated the real-time detection of superparamagnetic nanoparticles (SNPs), achieving a remarkable LOD of ∼528 μg/L. This advancement holds great potential for the label-free detection of magnetic biomarkers, e.g., ferritin, for the early diagnosis of diseases associated with iron overload, such as hereditary hemochromatosis (HHC).

Genetics of liver disease in adults

Chronic liver disease stands as a significant global health problem with an estimated 2 million annual deaths across the globe. Combining the use of next-generation sequencing technologies with evolving knowledge in the interpretation of genetic variation across the human genome is propelling our understanding, diagnosis, and management of both rare and common liver diseases. Here, we review the contribution of risk and protective alleles to common forms of liver disease, the rising number of monogenic diseases affecting the liver, and the role of somatic genetic variants in the onset and progression of oncological and non-oncological liver diseases. The incorporation of genomic information in the diagnosis and management of patients with liver disease is driving the beginning of a new era of genomics-informed clinical hepatology practice, facilitating personalized medicine, and improving patient care.

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.

Hemochromatosis Affects the Distribution of 68 Ga-DOTATATE in the Liver and Spleen

ABSTRACT

Hemosiderosis is a chronic condition characterized by abnormal iron accumulation in tissues. In a PET scan of a 37-year-old woman, we observed an irregular distribution of 68 Ga-DOTATATE in the liver and spleen. Specifically, 68 Ga-DOTATATE appeared to be concentrated primarily in the peripheral regions of these organs, creating a distinctive "shell-like" appearance. This peculiar pattern may be attributed to the substantial accumulation of hemosiderin in the liver and spleen.

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.

Analysis of anemia and iron supplementation among glioblastoma patients reveals sex-biased association between anemia and survival

The association between anemia and outcomes in glioblastoma patients is unclear. We analyzed data from 1346 histologically confirmed adult glioblastoma patients in the TriNetX Research Network. Median hemoglobin and hematocrit levels were quantified for 6 months following diagnosis and used to classify patients as anemic or non-anemic. Associations of anemia and iron supplementation of anemic patients with median overall survival (median-OS) were then studied. Among 1346 glioblastoma patients, 35.9% of male and 40.5% of female patients were classified as anemic using hemoglobin-based WHO guidelines. Among males, anemia was associated with reduced median-OS compared to matched non-anemic males using hemoglobin (HR 1.24; 95% CI 1.00-1.53) or hematocrit-based cutoffs (HR 1.28; 95% CI 1.03-1.59). Among females, anemia was not associated with median-OS using hemoglobin (HR 1.00; 95% CI 0.78-1.27) or hematocrit-based cutoffs (HR: 1.10; 95% CI 0.85-1.41). Iron supplementation of anemic females trended toward increased median-OS (HR 0.61; 95% CI 0.32-1.19) although failing to reach statistical significance whereas no significant association was found in anemic males (HR 0.85; 95% CI 0.41-1.75). Functional transferrin-binding assays confirmed sexually dimorphic binding in resected patient samples indicating underlying differences in iron biology. Anemia among glioblastoma patients exhibits a sex-specific association with survival.

Alcohol Use Unmasking Heterozygous Hereditary Hemochromatosis

Hereditary hemochromatosis (HH) is an autosomal recessive disorder characterized by excess iron absorption in the body following a mutation in the HFE gene. Though prolonged iron deposition has been shown to cause clinical symptoms such as hyperpigmentation, arthralgias, and liver damage, many individuals remain asymptomatic and exhibit no signs of iron overload. Here, we present a case where a 34-year-old with a history of severe alcohol use disorder presented with high iron, ferritin and transferrin saturation levels indicative of iron overload. Further testing for HFE gene mutations revealed simple heterozygote C282Y status, confirming the diagnosis of hereditary hemochromatosis. Simple heterozygotes, however, typically do not present with any symptoms of iron overload. This patient was counseled on lifestyle modifications which included abstaining from alcohol and reducing iron and vitamin C intake. As a result, his iron panel parameters improved. Thus, our case highlights that excessive alcohol consumption can exacerbate hereditary hemochromatosis and risk for overload even among heterozygotes.

Perturbations in lipid metabolism and gut microbiota composition precede cardiac dysfunction in a mouse model of thalassemia

Cardiomyopathy is a major complication of thalassemia, yet the precise underlying molecular mechanisms remain unclear. We examined whether altered lipid metabolism is an early driving factor in the development of cardiomyopathy using the Th3/+ mouse model of thalassemia. At age 20 weeks, male and female Th3/+ mice manifested anemia and iron overload; however, only males displayed metabolic defects and altered cardiac function. Untargeted lipidomics indicated that the circulating levels of 35 lipid species were significantly altered in Th3/+ mice compared to wild-type controls: triglycerides (TGs) with saturated fatty acids (FAs; TG42:0 and TG44:0) were elevated, while TGs with unsaturated FAs (TG(18:2_20:5_18:2 and TG54:8)) were reduced. Similarly, phosphatidylcholines (PCs) with long chain FAs (palmitic (16:0) or oleic (18:1)) were increased, while PCs with polyunsaturated FAs decreased. Circulating PC(16:0_14:0), GlcCer(d18:1/24:0) correlated significantly with iron overload and cardiac hypertrophy. 16S rRNA gene profiling revealed alterations in the intestinal microbiota of Th3/+ mice. Differentially abundant bacterial genera correlated with PC(39:6), PC(18:1_22:6), GlcCer(d18:1/24:1) and CE(14:0). These results provide new knowledge on perturbations in lipid metabolism and the gut microbiota of Th3/+ mice and identify specific factors which may represent early biomarkers or therapeutic targets to prevent development of cardiomyopathy in β-thalassemia.

Rusfertide for the treatment of iron overload in HFE-related haemochromatosis: an open-label, multicentre, proof-of-concept phase 2 trial

BACKGROUND

Hereditary haemochromatosis protein (HFE)-related haemochromatosis, an inherited iron overload disorder caused by insufficient hepcidin production, results in excessive iron absorption and tissue and organ injury, and is treated with first-line therapeutic phlebotomy. We aimed to investigate the efficacy and safety of rusfertide, a peptidic mimetic of hepcidin, in patients with HFE-related haemochromatosis.

METHODS

This open-label, multicentre, proof-of-concept phase 2 trial was done across nine academic and community centres in the USA and Canada. Adults (aged ≥18 years) with HFE-related haemochromatosis on a stable therapeutic phlebotomy regimen (maintenance phase) for at least 6 months before screening and who had a phlebotomy frequency of at least 0·25 per month (eg, at least three phlebotomies in 12 months or at least four phlebotomies in 15 months) and less than one phlebotomy per month, with serum ferritin of less than 300 ng/mL and haemoglobin of more than 11·5 g/dL, were eligible. Patients initiated 24 weeks of subcutaneous rusfertide treatment within 7 days of a scheduled phlebotomy at 10 mg once weekly. Rusfertide doses and dosing schedules could be adjusted to maintain serum transferrin iron saturation (TSAT) at less than 40%. During rusfertide treatment, investigators were to consider the need for phlebotomy when the serum ferritin and TSAT values exceeded the patient's individual pre-phlebotomy serum ferritin and TSAT values. No primary endpoint or testing hierarchy was prespecified. Prespecified efficacy endpoints included the change in the frequency of phlebotomies; the proportion of patients achieving phlebotomy independence; change in serum iron, TSAT, serum transferrin, serum ferritin, and liver iron concentration (LIC) as measured by MRI; and treatment-emergent adverse events (TEAEs). The key efficacy analyses for phlebotomy rate and LIC were conducted by use of paired t tests in the intention-to-treat population, defined as all patients who received any study drug and who had pretreatment and at least one post-dose measurement. We included all participants who received at least one dose of rusfertide in the safety analyses. This trial is closed and completed and is registered with ClinicalTrials.gov, NCT04202965.

FINDINGS

Between March 11, 2020, and April 23, 2021, 28 patients were screened and 16 (ten [63%] men and six [38%] women) were enrolled. 16 were included in analyses of phlebotomy endpoints and 14 for the LIC endpoint. 12 (75%) patients completed 24 weeks of treatment. The mean number of phlebotomies was significantly reduced during the 24-week rusfertide treatment (0·06 phlebotomies [95% CI -0·07 to 0·20]) compared with 24 weeks pre-study (2·31 phlebotomies [95% CI 1·77 to 2·85]; p<0·0001). 15 (94%) of 16 patients were phlebotomy-free during the treatment period. Mean LIC in the 14 patients in the intention-to-treat population was 1·4 mg iron per g dry liver weight (95% CI 1·0 to 1·8) at screening and 1·1 mg iron per g dry liver weight (95% CI 0·9 to 1·3) at the end of treatment (p=0·068). Mean TSAT was 45·3% (95% CI 33·2 to 57·3) at screening, 36·7% (24·2 to 49·2) after the pretreatment phlebotomy, 21·8% (15·8 to 27·9) 24 h after the first dose of rusfertide, 40·4% (27·1 to 53·8) at the end of treatment, and 32·6% (25·0 to 40·1) over the treatment duration. Mean serum iron was 24·6 μmol/L (95% CI 18·6 to 30·6), 20·1 μmol/L (14·8 to 25·3), 11·9 μmol/L (9·2 to 14·7), 22·5 μmol/L (15·9 to 29·1), and 19·0 μmol/L (15·3 to 22·6) at these same timepoints, respectively. Mean serum ferritin was 83·3 μg/L (52·2 to 114.4), 65·5 μg/L (32·1 to 98·9), 62·8 μg/L (33·8 to 91·9), 150·0 μg/L (86·6 to 213.3), and 94·3 μg/L (54·9 to 133.6) at these same timepoints, respectively. There were only minor changes in serum transferrin concentration. 12 (75%) patients had at least one TEAE, the most common of which was injection site pain (five [31%] patients). All TEAEs were mild or moderate in severity, except for a serious adverse event of pancreatic adenocarcinoma, which was considered severe and unrelated to treatment and was pre-existing and diagnosed 21 days after starting rusfertide treatment.

INTERPRETATION

Rusfertide prevents iron re-accumulation in the absence of phlebotomies and could be a viable therapeutic option for selected patients with haemochromatosis.

FUNDING

Protagonist Therapeutics.

Genome-wide prediction of pathogenic gain- and loss-of-function variants from ensemble learning of a diverse feature set

Gain-of-function (GOF) variants give rise to increased/novel protein functions whereas loss-of-function (LOF) variants lead to diminished protein function. Experimental approaches for identifying GOF and LOF are generally slow and costly, whilst available computational methods have not been optimized to discriminate between GOF and LOF variants. We have developed LoGoFunc, a machine learning method for predicting pathogenic GOF, pathogenic LOF, and neutral genetic variants, trained on a broad range of gene-, protein-, and variant-level features describing diverse biological characteristics. LoGoFunc outperforms other tools trained solely to predict pathogenicity for identifying pathogenic GOF and LOF variants and is available at https://itanlab.shinyapps.io/goflof/ .

Sex differences in chronic liver disease and benign liver lesions

The epidemiology, natural history, and therapeutic responses of chronic liver diseases and liver lesions often vary by sex. In this review, we summarize available clinical and translational data on these aspects of the most common liver conditions encountered in clinical practice, including the potential contributions of sex hormones to the underlying pathophysiology of observed differences. We also highlight areas of notable knowledge gaps and discuss sex disparities in access to liver transplant and potential strategies to address these barriers. Given established sex differences in immune response, drug metabolism, and response to liver-related therapies, emerging clinical trials and epidemiological studies should prioritize dedicated analyses by sex to inform sex-specific approaches to liver-related care.

Association of plasma iron with the risk of incident cancer in Chinese adults with hypertension: a nested case-control study

Background

Iron is an essential element for organismal health but excessive iron is potentially toxic. However, few observational studies link plasma iron (PI) concentrations and cancer risk, and the results are inconsistent.

Objective

This study aimed to explore the associations of PI concentrations with cancer risk in Chinese adults with hypertension.

Methods

We conducted a nested, case-control study, including 223 pairs of incident cancer cases and matched controls from the China Stroke Primary Prevention Trial. The median time between blood sample collection and subsequent cancer event occurrence was 2.13 years. The odds ratio (OR) and 95% confidence interval (CI) for the risk of cancer by PI were estimated from multivariable conditional logistic regression models.

Results

There was a nonlinear association between PI concentrations and total cancer risk. When compared with participants in tertile 2 of PI, the ORs of total cancer were 2.17 (95%CI: 1.25-3.85) and 1.29 (95%CI: 0.77-2.19) in participants in PI tertiles 3 and 1, respectively. Furthermore, higher PI was associated with increased digestive system cancer risk (OR=3.25, 95%CI:1.29-8.90), while lower PI was associated with increased risk of non-digestive system cancer (OR=3.32, 95%CI: 1.39-8.71). In a sensitivity analysis, the increases in total cancer risk or digestive system cancer risk were still observed with higher PI after excluding cancer cases occurring within the first year.

Conclusion

Our results showed an increased risk of cancer related to higher PI or lower PI in Chinese adults with hypertension. Higher iron levels were linked to an increased risk of digestive system cancers, whereas lower iron levels were linked to an increased risk of non-digestive system cancers.

Using Mendelian Randomization to Study the Role of Iron in Health and Disease

Iron has been shown to play a dual role in health and disease, with either a protective or harmful effect. Some of the contradictory findings from observational studies may be due to reverse causation, residual confounding, or small sample size. One approach that may overcome these limitations without the high cost of randomized control trials is the use of Mendelian randomization to examine the long-term role of iron in a variety of health outcomes. As there is emerging evidence employing Mendelian randomization as a method of assessing the role of micronutrients in health and disease, this narrative review will highlight recent Mendelian randomization findings examining the role of iron in cardiometabolic disorders, inflammation, neurological disorders, different cancers, and a number of other health-related outcomes.

Iron Load Toxicity in Medicine: From Molecular and Cellular Aspects to Clinical Implications

Iron is essential for all organisms and cells. Diseases of iron imbalance affect billions of patients, including those with iron overload and other forms of iron toxicity. Excess iron load is an adverse prognostic factor for all diseases and can cause serious organ damage and fatalities following chronic red blood cell transfusions in patients of many conditions, including hemoglobinopathies, myelodyspasia, and hematopoietic stem cell transplantation. Similar toxicity of excess body iron load but at a slower rate of disease progression is found in idiopathic haemochromatosis patients. Excess iron deposition in different regions of the brain with suspected toxicity has been identified by MRI T2* and similar methods in many neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Based on its role as the major biological catalyst of free radical reactions and the Fenton reaction, iron has also been implicated in all diseases associated with free radical pathology and tissue damage. Furthermore, the recent discovery of ferroptosis, which is a cell death program based on free radical generation by iron and cell membrane lipid oxidation, sparked thousands of investigations and the association of iron with cardiac, kidney, liver, and many other diseases, including cancer and infections. The toxicity implications of iron in a labile, non-protein bound form and its complexes with dietary molecules such as vitamin C and drugs such as doxorubicin and other xenobiotic molecules in relation to carcinogenesis and other forms of toxicity are also discussed. In each case and form of iron toxicity, the mechanistic insights, diagnostic criteria, and molecular interactions are essential for the design of new and effective therapeutic interventions and of future targeted therapeutic strategies. In particular, this approach has been successful for the treatment of most iron loading conditions and especially for the transition of thalassemia from a fatal to a chronic disease due to new therapeutic protocols resulting in the complete elimination of iron overload and of iron toxicity.

Accurate rare variant phasing of whole-genome and whole-exome sequencing data in the UK Biobank

Phasing involves distinguishing the two parentally inherited copies of each chromosome into haplotypes. Here, we introduce SHAPEIT5, a new phasing method that quickly and accurately processes large sequencing datasets and applied it to UK Biobank (UKB) whole-genome and whole-exome sequencing data. We demonstrate that SHAPEIT5 phases rare variants with low switch error rates of below 5% for variants present in just 1 sample out of 100,000. Furthermore, we outline a method for phasing singletons, which, although less precise, constitutes an important step towards future developments. We then demonstrate that the use of UKB as a reference panel improves the accuracy of genotype imputation, which is even more pronounced when phased with SHAPEIT5 compared with other methods. Finally, we screen the UKB data for loss-of-function compound heterozygous events and identify 549 genes where both gene copies are knocked out. These genes complement current knowledge of gene essentiality in the human genome.

Association Between Ferritin Levels and Altitude-Dependent Cardiorespiratory Fitness in Mountain Guides

Pühringer, Reinhard, Martina Muckenthaler, and Martin Burtscher. Association between ferritin levels and altitude-dependent cardiorespiratory fitness in mountain guides. High Alt Med Biol. 24:139-143, 2023. Background: Higher ferritin levels may be associated with lower cardiorespiratory fitness (CRF; i.e., maximal oxygen uptake, VO2max) and may represent early markers of cardiovascular risk but may also support high-altitude acclimatization. To evaluate these potential associations, data recordings from a large sample of male mountain guides have been analyzed. Methods: A total of 154 data sets (including anthropometric data, VO2max, blood lipids, hemoglobin, ferritin, and transferrin levels) of regularly physically active and well-acclimatized mountain guides were available for analyses. Participants performed equal incremental cycle ergometer tests to exhaustion at low (600 m) and (∼1 week later) at moderate altitude (2,000 m). Results: Ferritin levels were positively correlated with levels of hemoglobin (r = 0.29, p < 0.01), total cholesterol (r = 0.18, p < 0.05), triglycerides (r = 0.23, p < 0.01), and low-density lipoprotein (r = 0.22, p < 0.01), and negatively with high-density lipoprotein levels (r = -0.16, p < 0.05) and also with baseline (taken at low altitude) VO2max values (r = -0.19, p < 0.05). In contrast, higher ferritin levels were associated with less VO2max decline from low-to-moderate altitude (r = 0.26, p < 0.01). Conclusion: Higher ferritin levels in male mountain guides are weakly associated with lower CRF and higher prevalence of cardiovascular risk factors but with slightly less reduction in VO2max when acutely exposed to moderate altitude. The clinical relevance of these observations needs further investigation.

Haemochromatosis

Haemochromatosis is one of the most common genetic diseases affecting patients of northern European ancestry. It is overdiagnosed in patients without iron overload and is underdiagnosed in many patients. Early diagnosis by genetic testing and therapy by periodic phlebotomy can prevent the most serious complications, which include liver cirrhosis, liver cancer, and death. This Seminar includes an update on the origins of haemochromatosis; and an overview pathophysiology, genetics, natural history, signs and symptoms, differential diagnoses, treatment with phlebotomy, outcomes, and future directions.

Hereditary hemochromatosis beyond hyperferritinemia: Clinical and laboratory investigation of the patient's profile submitted to phlebotomy in two reference centers in southern Brazil

Hereditary Hemochromatosis is a disorder characterized by iron deposition in several organs and hyperferritinemia. The most studied variants are linked to the HFE gene. In Brazil, surveys that characterize this population are scarce, with no sampling in the state of Rio Grande do Sul. Our objective is to carry out a data collection focusing on the profile of this population and the influence of the most frequently HFE variants. Two centers were enrolled: Hospital de Clínicas de Porto Alegre and Hospital São Vicente de Paulo. Patients with hyperferritinemia and undergoing phlebotomy were invited. Clinical data were collected, including HFE investigation. Among the descriptive data, the allele frequency of the C282Y variant (0.252) stands out, which differs from the national scenario. Systemic arterial hypertension was the most cited comorbidity. Differences between centers were observed, highlighting higher frequency of H63D cases in HSVP (p<0.01). Genotypes were stratified according to deleterious effect of C282Y variant. Higher transferrin saturation and number of phlebotomies were observed in the C282Y/C282Y cases (p<0.001). Positive family history for hyperferritinemia was more prevalent in compound heterozygotes (p<0.01). The results presented confirm the importance of encouraging such studies and reiterate the need for greater attention to this population.

Iron metabolism and atherosclerosis

Despite several decades of study, whether iron is involved in the development of atherosclerosis remains a controversial and unresolved issue. Here, we focus on the up-to-date advances in studies on role of iron in atherosclerosis and discuss possible reasons why patients with hereditary hemochromatosis (HH) do not show any increased incidence of atherosclerosis. In addition, we analyze conflicting results concerning the role of iron in atherogenesis from several epidemiological and animal studies. We argue that atherosclerosis is not observed in HH because iron homeostasis in the arterial wall, the actual location of atherosclerosis, is not significantly affected, and support a causal link between iron in the arterial wall and atherosclerosis.

The ancestral haplotype markers HLA -A3 and B7 do not influence the likelihood of advanced hepatic fibrosis or cirrhosis in HFE hemochromatosis

Advanced hepatic fibrosis occurs in up to 25% of individuals with C282Y homozygous hemochromatosis. Our aim was to determine whether human leukocyte antigen (HLA)-A3 and B7 alleles act as genetic modifiers of the likelihood of advanced hepatic fibrosis. Between 1972 and 2013, 133 HFE C282Y homozygous individuals underwent clinical and biochemical evaluation, HLA typing, liver biopsy for fibrosis staging and phlebotomy treatment. Hepatic fibrosis was graded according to Scheuer as F0-2 (low grade hepatic fibrosis), F3-4 (advanced hepatic fibrosis), and F4 cirrhosis. We analysed associations between the severity of fibrosis and HLA-A3 homozygosity, heterozygosity or absence, with or without the presence of HLA-B7 using categorical analysis. The mean age of HLA-A3 homozygotes (n = 24), heterozygotes (n = 65) and HLA-A3 null individuals (n = 44) was 40 years. There were no significant differences between the groups for mean(± SEM) serum ferritin levels (1320 ± 296, 1217 ± 124, 1348 ± 188 [Formula: see text]g/L), hepatic iron concentration (178 ± 26, 213 ± 22, 199 ± 29 [Formula: see text]mol/g), mobilizable iron stores (9.9 ± 1.5, 9.5 ± 1.5, 11.5 ± 1.7 g iron removed via phlebotomy), frequency of advanced hepatic fibrosis (5/24[12%], 13/63[19%], 10/42[19%]) or cirrhosis (3/24[21%], 12/63[21%], 4/42[24%]), respectively. The presence or absence of HLA-B7 did not influence the outcome. Thus, HLA-A3 and HLA-B7 alleles are not associated with the risk of advanced hepatic fibrosis or cirrhosis in C282Y hemochromatosis.

Clinical and Forensic Signs Resulting from Exposure to Heavy Metals and Other Chemical Elements of the Periodic Table

Several heavy metals and other chemical elements are natural components of the Earth's crust and their properties and toxicity have been recognized for thousands of years. Moreover, their use in industries presents a major source of environmental and occupational pollution. Therefore, this ubiquity in daily life may result in several potential exposures coming from natural sources (e.g., through food and water contamination), industrial processes, and commercial products, among others. The toxicity of most chemical elements of the periodic table accrues from their highly reactive nature, resulting in the formation of complexes with intracellular compounds that impair cellular pathways, leading to dysfunction, necrosis, and apoptosis. Nervous, gastrointestinal, hematopoietic, renal, and dermatological systems are the main targets. This manuscript aims to collect the clinical and forensic signs related to poisoning from heavy metals, such as thallium, lead, copper, mercury, iron, cadmium, and bismuth, as well as other chemical elements such as arsenic, selenium, and fluorine. Furthermore, their main sources of occupational and environmental exposure are highlighted in this review. The importance of rapid recognition is related to the fact that, through a high degree of suspicion, the clinician could rapidly initiate treatment even before the toxicological results are available, which can make a huge difference in these patients' outcomes.

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.

Amlodipine rescues advanced iron overload cardiomyopathy in hemojuvelin knockout murine model: Clinical implications

Background

Iron overload cardiomyopathy (IOC) is a major co-morbidity of genetic hemochromatosis and secondary iron overload with limited therapeutic options. We aim to investigate mechanisms of rescue action of amlodipine in the murine model of iron overload, characterize changes in human cardiac tissue due to IOC, and compare them to the changes in the animal model of IOC.

Methods and results

As an animal model, we used male hemojuvelin knockout (HJVKO) mice, which lacked hemojuvelin (a co-receptor protein for hepcidin expression). The mice were fed a high-iron diet from 4 weeks to 1 year of age. As a rescue, iron-fed mice received the Ca²⁺ channel blocker, amlodipine, from 9 to 12 months. Iron overload resulted in systolic and diastolic dysfunctions and changes in the cardiac tissue similar to the changes in the explanted human heart with IOC. An IOC patient (β-thalassemia) with left-ventricular ejection fraction (LVEF) 25% underwent heart transplantation. The murine model and the explanted heart showed intra-myocyte iron deposition, fibrosis, hypertrophy, oxidative stress, remodeling of Ca²⁺ cycling proteins, and metabolic kinases typical of heart failure. Single-myocyte contractility and Ca²⁺ release were diminished in the murine model. The amlodipine-treated group exhibited normalization of cellular function and reversed fibrosis, hypertrophy, oxidative stress, and metabolic remodeling. We also report a clinical case of primary hemochromatosis successfully treated with amlodipine.

Conclusions

The aged HJVKO murine model on the iron-rich diet reproduced many features of the human case of IOC. The use of amlodipine in the murine model and clinical case reversed IOC remodeling, demonstrating that amlodipine is effective adjuvant therapy for IOC.

Sudden Onset Iron Overload Cardiomyopathy After Liver Transplantation

Iron overload cardiomyopathy has been described in patients who develop acute heart failure after liver transplantation but few reports of this are available. We present a case of a patient with end-stage liver disease who underwent a deceased donor liver transplantation and developed acute onset systolic heart failure with reduced left ventricular ejection fraction. A cardiac magnetic resonance image demonstrated late gadolinium enhancement with diffuse enhancement globally and T1 mapping with severely decreased pre-contrast T1 values suggesting iron overload cardiomyopathy. The patient was treated with iron chelating therapy as well as heart failure guideline-directed medical therapy with subsequent improvement in cardiac function on follow-up magnetic resonance images. Despite our patient's diagnosis of iron overload cardiomyopathy, her iron studies showed normal serum iron and ferritin levels and no evidence of hepatic iron deposition in the transplanted liver.

HFE hemochromatosis in African Americans: Prevalence estimates of iron overload and iron overload-related disease

BACKGROUND

Little is known about the prevalence of HFE (homeostatic iron regulator) hemochromatosis in African Americans (AA).

METHODS

We defined AA as self-identified AA, blacks, or non-Hispanic blacks. We defined hemochromatosis-associated HFE genotypes as p.C282Y/p.C282Y and p.C282Y/p.H63D. We compiled prevalences of these genotypes in AA using published population and cohort data and numbers of men and women ≥18 y‬ in 2018 U.S. Census estimates. We defined iron overload (IO) and IO-related disease by genotype as previously reported in population and cohort studies of hemochromatosis in whites of European ancestry. We used these definitions to estimate prevalences and numbers of AA with IO and IO-related disease associated with hemochromatosis-associated HFE genotypes.

RESULTS

There were ∼16,287,599 men and ∼17,644,898 women. HFE genotypes and their respective prevalences were: p.C282Y/p.C282Y, 0.00017 (6/34,905) [95% confidence interval 0.000034, 0.00031] and p.C282Y/p.H63D, 0.0012 (41/33,596) [0.000084, 0.0016]. IO prevalences were: men 0.000076 [0.000072, 0.000081] and women 0.0000061 [0.0000050, 0.0000073]. IO-related disease prevalences were: men 0.000063 [0.000059, 0.000067] and women 0.0000021 [0.0000014, 0.0000027]. There were ∼1021 [961, 1091] men and ∼36 [25, 48] women with IO-related disease.

CONCLUSIONS

We conclude that ∼1/25,061 AA >18 y have a hemochromatosis-associated HFE genotype and IO and that ∼1/32,103 AA >18 y have a hemochromatosis-associated HFE genotype and IO-related disease.

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.