Clinical Penetrance of Hereditary Hemochromatosis-Related End-Organ Damage of C282Y Homozygosity, A Newfoundland Experience

A Review of New Concepts in Iron Overload

Iron overload disorders are conditions that can lead to increased body iron stores and end-organ damage in affected organs. Increased iron deposition most commonly occurs in the liver, heart, endocrine system, joints, and pancreas. Iron overload disorders may be caused by genetic or acquired causes (transfusion, dyserythropoiesis, and chronic liver disease). The HFE gene C282Y homozygous mutation is the most common cause of hereditary hemochromatosis (HH). Other genes implicated in HH include TFR2, HAMP, HJV, and SLC40A1. In the past 2 decades, there have been major advances in the understanding of genetic iron overload disorders. Furthermore, new novel techniques to measure iron content in organs noninvasively, as well as new therapeutic options for the treatment of HH, are currently under development. This article focuses on the latest concepts in understanding, diagnosing, and managing genetic iron overload disorders, particularly HH.

Screening for Hereditary Hemochromatosis in Newly Referred Diabetes Mellitus

Aims

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

Methods

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

Results

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

Conclusions

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

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.

Risk of Hepatocellular Carcinoma in Patients with Various HFE Genotypes

BACKGROUND AND AIMS

Hereditary hemochromatosis (HH) is associated with increased risk of hepatocellular carcinoma (HCC). However, HCC risk factors within this population and across various HFE genotypes remain unclear.

METHODS

We conducted a retrospective cohort study of patients with ≥ 1 HFE genotype test in the Veterans Health Administration. We followed patients until HCC, death, or 6/30/19. We calculated incidence rates (IRs) and used Cox proportional hazards models to estimate HCC risk. In patients with type-1 HH genotypes (C282Y/C282Y or C282Y/H63D), we examined risk factors for HCC.

RESULTS

We identified 5225 patients: 260 were C282Y/C282Y; 227 were C282Y/H63D; 436 were H63D heterozygous; 535 had other HFE mutations; 3767 without mutation. IR for C282Y/C282Y homozygotes (5.59/1000 PYs) and C282Y/H63D compound heterozygotes (4.12/1000 PYs) were significantly higher than controls (0.92/1000 PYs) with adjusted hazard ratio (adj HR), 95% CI 8.80, 4.17-18.54; and 5.25, 2.24-12.32, respectively. HCC risk was higher in H63D heterozygote than controls (adj HR = 2.82, 95% CI 1.21-6.58); cases were related to non-alcoholic fatty liver disease. Among patients with HH, age ≥ 65 (adj HR = 2.2, 95% CI 0.47-10.27), diabetes (adj HR 3.74, 95% CI 1.25-11.20) and high baseline aspartate-aminotransferase to platelet ratio-index (APRI, adj HR = 3.91, 95% CI 1.29-11.89) had higher risk. Among patients with high baseline ferritin, persistent ferritin > 250 ng/mL had higher risk.

CONCLUSION

HCC risk was high in C282Y homozygous and C282Y/H63D patients. These HFE genotypes, older age, diabetes, high APRI/ferritin levels were associated with increased risk. While H63D heterozygous genotype was associated with HCC risk, this association might be due to metabolic factors.

Hereditary hemochromatosis: data from a single center Copenhagen cohort

OBJECTIVES

We aimed to describe a cohort of hereditary hemochromatosis (HH) patients from a single urban center in Copenhagen.

METHODS

Retrospectively, data from patients with HH from the years 2009-2020 were collected.

RESULTS

A total of 203 patients was recorded. Males constituted 65.0% of the patients. Homozygous HH (HHH)/compound heterozygous HH (CHH) accounted for 69.4%/30.6%. HHH patients had significantly higher ferritin and transferrin saturation (TS) levels at debut than CHH patients. Fifty-five HHH patients (39.0%) had ferritin >1000 ug/L versus 9 (14.5%) in the CHH group (p < .001). Age at debut did not differ between female and male patients. Ferritin (but not TS) levels were significantly higher in male patients. The proportion of patients with ferritin >1000 did not differ between males and females. One-hundred patients (49.3%) had one or more symptoms at the time of diagnosis; arthralgias of the metacarpophalangeal joints and/or ankles (n = 46 (22.7%)), fatigue (n = 67 (33.0%)) and decreased libido (n = 20 (9.9%)). The proportion of patients with symptoms did not differ between HHH and CHH or between male and female patients. Severe organ complications (cardiomyopathy, late onset type 1 diabetes or cirrhosis) were present in 14 patients (6.9%).

CONCLUSIONS

We report a high proportion of compound HH, constituting almost one-third of patients. We found that the proportion of patients with symptoms did not differ between HHH and CHH and recommend that CHH should be treated and examined in the same way as HHH.

C282Y/H63D Compound Heterozygosity Is a Low Penetrance Genotype for Iron Overload-related Disease

Background

Hereditary hemochromatosis (HH) occurs due to mutations in the HFE gene. While the C282Y mutation is the most common genotype reported in HH, other genotypes are found less frequently, indicating variable degrees of penetrance. We studied the penetrance of the C282Y/H63D compound heterozygote genotype in developing clinically significant iron overload.

Methods

We have completed a retrospective analysis on every individual within Newfoundland & Labrador who were diagnosed as C282Y/H63D compound heterozygote between 1996 and 2009 through a molecular genetics study. We collected data for up to 10 years following the initial genotyping using electronic health records, including laboratory values, phlebotomy status, radiologic reports and clinic records. Iron overload status was classified based on the HealthIron study.

Results

Between 1996 and 2009, 247 individuals with available health records tested positive for C282Y/H63D compound heterozygosity. Over the 10 years of our study, 5.3% of patients exhibited iron overload-related disease on the background of documented iron overload. Including these individuals, 10.1% of patients had documented iron overload, 23.1% of patients had a provisional iron overload and the remaining 66.8% of patients had no evidence of iron overload. Only 44 patients had documented phlebotomies, likely based on their severe phenotype at baseline. Despite phlebotomy, the prevalence of iron overload was higher among these patients. The penetrance of compound heterozygosity was also significantly higher among men (P &lt; 0.01).

Conclusion

C282Y/H63D compound heterozygosity is a low penetrance genotype in HH. This is the largest reported cohort of C282Y/H63D compound heterozygotes in North America with an extended follow-up.

Survival and development of health conditions after iron depletion therapy in C282Y-linked hemochromatosis patients

BACKGROUND

We report long-term survival and development of selected health conditions in Ontario-based referred and screened C282Y homozygotes for hemochromatosis treated by phlebotomy compared with an untreated control group known to be without HFE mutations.

METHODS

Patient characteristics and outcomes (all-cause mortality, liver cancer, diabetes, cirrhosis, hip or knee joint replacement, and osteoarthritis) were ascertained using a linked health administrative database held at ICES. Outcomes were assessed between groups without the outcome at baseline using Cox proportional hazards regression adjusted for age and sex. All C282Y homozygotes with elevated serum ferritin were treated by phlebotomy to reach serum ferritin of 50 µg/L. Our cohort included 527 C282Y homozygotes (311 men, 216 women, mean age 48 years) and 12,879 control participants (5,667 men and 7,212 women).

RESULTS

C282Y homozygotes had an increased risk of all-cause mortality (aHR 1.44 [1.19-1.75], p <0.001); hepatocellular carcinoma (aHR 8.30 [3.97-17.34], p <0.001); hip or knee joint replacement (aHR 3.06 [2.46-3.81], p <0.001); osteoarthritis (aHR 1.72 [1.47-2.01], p <0.001); and cirrhosis (aHR 3.87 [3.05-4.92], p <0.001). C282Y homozygotes did not have an increased risk for diagnosis of diabetes) (aHR 0.84 [0.67-1.07], p = 0.16) during follow-up (median 17.7 y).

CONCLUSIONS

C282Y homozygotes experience higher death and complication rates than individuals without HFE mutations, despite treatment by phlebotomy. Diabetes did not increase after phlebotomy therapy.

Haemochromatosis in a kidney transplant recipient: a case report

BACKGROUND

Iron overload is inevitably related to chronic kidney disease (CKD) treatment. Haemochromatosis leads to multiorgan damage and is associated with increased mortality. Primary haemochromatosis is the most common autosomal recessive disease in white populations. In most cases, the classic form of hereditary haemochromatosis is caused by mutations, mainly C282Y and H63D, in the haemochromatosis gene (HFE). Secondary haemochromatosis can be triggered by iron administration and blood transfusions. Haemochromatosis is rarely reported in kidney transplant recipients. Atypical factors may evoke haemochromatosis in patients without HFE mutations or other standard risk factors.

CASE PRESENTATION

In the current study, we present a patient who started to have haemochromatosis symptoms after kidney transplantation. A 37-year-old man after kidney transplantation from a deceased donor was admitted to the hospital due to high serum ferritin levels and impaired graft function. The patient's past medical history included arterial hypertension, embolization of both renal arteries and necrosis of the left femoral head. Glomerulonephritis was suspected as a cause of CKD; however, severe kidney failure was diagnosed, kidney biopsy was not performed, and the patient started intermittent haemodialysis. While on dialysis to treat anaemia, the patient had received erythropoietin and iron intravenously, and the maximal serum ferritin level was 2115 ng/ml. After kidney transplantation, ferritin levels started to increase rapidly, with a maximum level of 9468 ng/ml one and a half years after surgery. His genetic study showed HFE C282Y heterozygosity. Symptoms of haemochromatosis, such as skin hyperpigmentation, elevated activity of aminotransferases, impaired glucose tolerance and heart failure, were observed. Therapeutic phlebotomy was started, and 36 procedures were performed. After treatment, graft function significantly improved, most haemochromatosis symptoms resolved, and the serum ferritin level significantly decreased.

CONCLUSIONS

Haemochromatosis can occur in heterozygotic HFE patients after kidney transplantation. Iron administration, infections, type of immunosuppression and liver dysfunction should be considered potential triggers of haemochromatosis in this group of patients.