Hémochromatose héréditaire : circonstances de découverte et délais diagnostiques

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.

Joint manifestations revealing inborn metabolic diseases in adults: a narrative review

Inborn metabolic diseases (IMD) are rare conditions that can be diagnosed during adulthood. Patients with IMD may have joint symptoms and the challenge is to establish an early diagnosis in order to institute appropriate treatment and prevent irreversible damage. This review describes the joint manifestations of IMD that may be encountered in adults. The clinical settings considered were arthralgia and joint stiffness as well as arthritis. Unspecific arthralgias are often the first symptoms of hereditary hemochromatosis, chronic low back pain may reveal an intervertebral disc calcification in relation with alkaptonuria, and progressive joint stiffness may correspond to a mucopolysaccharidosis or mucolipidosis. Gaucher disease is initially revealed by painful acute attacks mimicking joint pain described as "bone crises". Some IMD may induce microcrystalline arthropathy. Beyond classical gout, there are also gouts in connection with purine metabolism disorders known as "enzymopathic gouts". Pyrophosphate arthropathy can also be part of the clinical spectrum of Gitelman syndrome or hypophosphatasia. Oxalate crystals arthritis can reveal a primary hyperoxaluria. Destructive arthritis may be indicative of Wilson's disease. Non-destructive arthritis may be seen in mevalonate kinase deficiency and familial hypercholesterolemia.

Case of Vibrio Vulnificus bacteremia in a patient heterozygous for HFE p.C282Y mutation and alcoholic liver cirrhosis

Vibrio vulnificus is a Gram-negative bacterium, a member of the Vibrionaceae family. V. vulnificus is the main cause of seafood-related deaths in the United States because it can cause severe wound infections or sepsis. This microorganism is highly dependent on iron availability. Therefore, patients with high body iron levels are more susceptible to the infection. Prompt treatment with cephalosporins as well as doxycycline is usually administered. We present a case of V. vulnificus bacteremia in a patient heterozygous for HFE p.C282Y mutation and underlying alcoholic liver cirrhosis.

Hereditary haemochromatosis presenting to rheumatology clinic as inflammatory arthritis

Hereditary haemochromatosis (HH) is the most commonly identified genetic disorder in Caucasians. HH has a wide variety of clinical manifestations. As such, the presenting complaint in new diagnoses of HH can be non-specific such as fatigue; however, joint symptoms such as arthralgia are also common. These joint symptoms closely mimic the features of other musculoskeletal diseases such as rheumatoid arthritis (RA). Early diagnosis of HH is key to prevent long-term irreversible complications such as liver damage, diabetes and degenerative joint disease. We present a case of HH which was initially suspected to be early RA, with ultrasound findings of active synovitis. High clinical suspicion, a raised serum ferritin followed by genetic testing for C282Y mutation confirmed the diagnosis of HH. The synovitis responded to corticosteroids and was suspected to be due to pseudogout a known complication of HH. Early diagnosis and treatment resulted in a favourable outcome.

Diagnosis and management of hereditary haemochromatosis

Hereditary haemochromatosis, one of the most common genetic disorders in the United States, can produce systemic iron deposition leading to end-organ failure and death if untreated. The diagnosis of this condition can be challenging as elevated serum ferritin may be seen in a variety of conditions, including acute and chronic liver disease, a range of systemic inflammatory states, and both primary and secondary iron overload syndromes. Appropriate and timely diagnosis of haemochromatosis is paramount as simple interventions, such as phlebotomy, can prevent or reverse organ damage from iron overload. The recognition of other aetiologies of elevated ferritin is also vital to ensure that appropriate intervention is provided and phlebotomy only utilized in patients who require it. In this review, we summarize the existing data on the work up and management of hereditary haemochromatosis and present a practical algorithm for the diagnosis and management of this disease.

Sporadic Porphyria Cutanea Tarda as the Initial Manifestation of Hereditary Hemochromatosis

Porphyria cutanea tarda (PCT) is a skin disorder characterized by abnormal heme synthesis. We present a 45-year-old man with intermittent skin lesions recurring annually for years. Skin biopsy and measurement of serum heme precursors confirmed a diagnosis of PCT. He had persistently elevated alanine and aspartate transferase. He was referred to hematology and had genetic testing with iron studies which also revealed hereditary hemochromatosis (HH). Therapeutic phlebotomy was initiated, which led to resolution of iron overload and skin lesions. We highlight the associated conditions of PCT and HH, their common therapy of phlebotomy, and initial manifestations of HH.

Diagnosis of hyperferritinemia in routine clinical practice

The discovery of hyperferritinemia is often fortuitous, revealed in results from a laboratory screening or follow-up test. The aim of the diagnostic procedure is therefore to identify its cause and to identify or rule out hepatic iron overload, in a three-stage process. In the first step, clinical findings and several simple laboratory tests are sufficient to detect four of the most frequent causes of high ferritin concentrations: alcoholism, inflammatory syndrome, cytolysis, and metabolic syndrome. None of these causes is associated with substantial hepatic iron overload. If transferrin saturation is high (> 50%), hereditary hemochromatosis will be considered in priority. In the second phase, rarer diseases will be sought. Among them, only chronic hematologic diseases (acquired or congenital) and excessive iron intake or infusions (patients on chronic dialysis and high-level athletes) are at risk of iron overload. In the third stage, if a doubt persists about the cause or if the ferritin concentration is very high or continues to rise, it is essential to verify the hepatic iron concentration to rule out overload. The principal examination to guide diagnosis and treatment is hepatic MRI to assess its iron concentration. It is essential to remember that more than 40% of patients with hyperferritinemia have several causes simultaneously present.

Cost-Effectiveness of Different Population Screening Strategies for Hereditary Haemochromatosis in Australia

INTRODUCTION

Amongst populations of northern European ancestry, HFE-associated haemochromatosis is a common genetic disorder characterised by iron overload. In the absence of treatment, excess iron is stored in parenchymal tissues, causing morbidity and mortality. Population screening programmes may increase early diagnosis and reduce associated disease. No contemporary health economic evaluation has been published for Australia. The objective of this study was to identify cost-effective screening strategies for haemochromatosis in the Australian setting.

METHODS

A Markov model using probabilistic decision analysis was developed comparing four adult screening strategies: the status quo (cascade and incidental screening), genotyping with blood and buccal samples and transferrin saturation followed by genotyping (TfS). Target populations were males (30 years) and females (45 years) of northern European ancestry. Cost-effectiveness was estimated from the government perspective over a lifetime horizon.

RESULTS

All strategies for males were cost-effective compared to the status quo. The incremental costs (standard deviation) associated with genotyping (blood) were AUD7 (56), TfS AUD15 (45) and genotyping (buccal) AUD63 (56), producing ICERs of AUD1673, 4103 and 15,233/quality-adjusted life-year (QALY) gained, respectively. For females, only the TfS strategy was cost-effective, producing an ICER of AUD10,195/QALY gained. Approximately 3% of C282Y homozygotes were estimated to be identified with the status quo approach, compared with 40% with the proposed screening strategies.

CONCLUSION

This model estimated that genotyping and TfS strategies are likely to be more cost-effective screening strategies than the status quo.

A systematic review of the association between fatigue and genetic polymorphisms

Fatigue is one of the most common and distressing symptoms, leading to markedly decreased quality of life among a large subset of patients with a variety of disorders. Susceptibility to fatigue may be influenced by genetic factors including single nucleotide polymorphisms (SNPs), especially in the regulatory regions, of relevant genes. To further investigate the association of SNPs with fatigue in various patient populations, a systematic search was conducted on Pubmed, CINAHL, PsycINFO, and Sociological Abstracts Database for fatigue related-terms in combination with polymorphisms or genetic variation-related terms. Fifty papers in total met the inclusion and exclusion criteria for this analysis. These 50 papers were further classified into three subgroups for evaluation: chronic fatigue syndrome (CFS), cancer-related fatigue (CRF) and other disease-related fatigue. SNPs in regulatory pathways of immune and neurotransmitter systems were found to play important roles in the etiologies of CFS, CRF and other disease-related fatigue. Evidence for associations between elevated fatigue and specific polymorphisms in TNFα, IL1b, IL4 and IL6 genes was revealed for all three subgroups of fatigue. We also found CFS shared a series of polymorphisms in HLA, IFN-γ, 5-HT and NR3C1 genes with other disease-related fatigue, however these SNPs (excluding IFN-γ) were not found to be adequately investigated in CRF. Gaps in knowledge related to fatigue etiology and recommendations for future research are further discussed.

Population Screening for Hereditary Haemochromatosis in Australia: Construction and Validation of a State-Transition Cost-Effectiveness Model

INTRODUCTION

HFE-associated haemochromatosis, the most common monogenic disorder amongst populations of northern European ancestry, is characterised by iron overload. Excess iron is stored in parenchymal tissues, leading to morbidity and mortality. Population screening programmes are likely to improve early diagnosis, thereby decreasing associated disease. Our aim was to develop and validate a health economics model of screening using utilities and costs from a haemochromatosis cohort.

METHODS

A state-transition model was developed with Markov states based on disease severity. Australian males (aged 30 years) and females (aged 45 years) of northern European ancestry were the target populations. The screening strategy was the status quo approach in Australia; the model was run over a lifetime horizon. Costs were estimated from the government perspective and reported in 2015 Australian dollars ($A); costs and quality-adjusted life-years (QALYs) were discounted at 5% annually. Model validity was assessed using goodness-of-fit analyses. Second-order Monte-Carlo simulation was used to account for uncertainty in multiple parameters.

RESULTS

For validity, the model reproduced mortality, life expectancy (LE) and prevalence rates in line with published data. LE for C282Y homozygote males and females were 49.9 and 40.2 years, respectively, slightly lower than population rates. Mean (95% confidence interval) QALYS were 15.7 (7.7-23.7) for males and 14.4 (6.7-22.1) for females. Mean discounted lifetime costs for C282Y homozygotes were $A22,737 (3670-85,793) for males and $A13,840 (1335-67,377) for females. Sensitivity analyses revealed discount rates and prevalence had the greatest impacts on outcomes.

CONCLUSION

We have developed a transparent, validated health economics model of C282Y homozygote haemochromatosis. The model will be useful to decision makers to identify cost-effective screening strategies.

Costs associated with hereditary haemochromatosis in Australia: a cost-of-illness study

Objective The aim of the present study was to assess health sector, other sector and time-related (productivity) costs associated with hereditary haemochromatosis from societal, government and patient perspectives for the Australian setting. Methods A national web-based survey of people with haemochromatosis was conducted between November 2013 and February 2015. Participants completed a health survey and resource use diaries. Costs were calculated using a bottom-up approach and calculated in 2015 Australian dollars. Results Cost data were available for 157 participants. From a societal perspective, the estimated annual cost of haemochromatosis was A$274 million. The mean (95% confidence interval) cost for symptomatic patients was almost threefold greater than that of asymptomatic patients (A$10030 (7705–12670) vs A$3701 (2423–5296) respectively). Health sector and productivity-related time loss were the main cost drivers. When extrapolating costs to the Australian population level, asymptomatic haemochromatosis accounted for higher costs than symptomatic haemochromatosis (A$183 million vs A$91 million), reflecting the low clinical penetrance estimate used. Total costs increased when higher clinical penetrance estimates were used. Conclusion The present cost-of-illness study, the first to be published for haemochromatosis, found that although costs were substantial, they could be decreased by reducing clinical penetrance. Development of cost-effective strategies to increase early diagnosis is likely to result in better health outcomes for patients and lower total costs. What is known about the topic? To date, no cost-of-illness study has been conducted for haemochromatosis. Previous economic work in this area has relied on cost estimates based on expert opinion. What does the paper add? This paper provides the first cost estimates for haemochromatosis for the Australian population. These estimates, calculated using a bottom-up approach, were extrapolated to the population level based on the most robust epidemiological estimates available for the Australian population. What are the implications for practitioners? Population screening programs have been widely suggested as an approach to reduce clinical penetrance; however, the lack of high-quality economic analyses has been cited as a barrier to implementation. The present study provides the most robust cost estimates to date, which may be used to populate economic models. In addition, the present study illustrates that reducing clinical penetrance of haemochromatosis is likely to result in substantial reductions in cost.

A Systematic Review and Narrative Synthesis of Health Economic Studies Conducted for Hereditary Haemochromatosis

BACKGROUND

Hereditary haemochromatosis (HH) is a common genetic condition amongst people of northern European heritage. HH is associated with increased iron absorption leading to parenchymal organ damage and multiple arthropathies. Early diagnosis and treatment prevents complications. Population screening may increase early diagnosis, but no programmes have been introduced internationally: a paucity of health economic data is often cited as a barrier.

OBJECTIVE

To conduct a systematic review of all health economic studies in HH.

METHODS

Studies were identified through electronic searching of economic/biomedical databases. Any study on HH with original economic component was included. Study quality was formally assessed. Health economic data were extracted and analysed through narrative synthesis.

RESULTS

Thirty-eight studies met the inclusion criteria. The majority of papers reported on costs or cost effectiveness of screening programmes. Whilst most concluded screening was cost effective compared with no screening, methodological flaws limit the quality of these findings. Assumptions regarding clinical penetrance, effectiveness of screening, health-state utility values (HSUVs), exclusion of early symptomatology (such as fatigue, lethargy and multiple arthropathies) and quantification of costs associated with HH were identified as key limitations. Treatment studies concluded therapeutic venepuncture was the most cost-effective intervention.

CONCLUSIONS

There is a paucity of high-quality health economic studies relating to HH. The development of a comprehensive HH cost-effectiveness model utilising HSUVs is required to determine whether screening is worthwhile.