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Magnetic resonance imaging of the pituitary gland in a patient with secondary hemochromatosis is described. On T1-weighted images, the anterior lobe had almost no signal intensity, and only the high-signal posterior lobe was seen. These findings are compatible with the distribution of iron deposition and clinical symptoms in hemochromatosis.
Hereditary hemochromatosis type 3 is an iron (Fe)-overload disorder caused by mutations in transferrin receptor 2 (TfR2). TfR2 is expressed highly in the liver and regulates Fe metabolism. The aim of this study was to investigate duodenal Fe absorption and hepatic Fe uptake in a TfR2 (Y245X) mutant mouse model of hereditary hemochromatosis type 3. Duodenal Fe absorption and hepatic Fe uptake were measured in vivo by 59Fe-labeled ascorbate in TfR2 mutant mice, wild-type mice, and Fe-loaded wild-type mice (2% dietary carbonyl Fe). Gene expression was measured by real-time RT-PCR. Liver nonheme Fe concentration increased progressively with age in TfR2 mutant mice compared with wild-type mice. Fe absorption (both duodenal Fe uptake and transfer) was increased in TfR2 mutant mice compared with wild-type mice. Likewise, expression of genes participating in duodenal Fe uptake (Dcytb, DMT1) and transfer (ferroportin) were increased in TfR2 mutant mice. Nearly all of the absorbed Fe was taken up rapidly by the liver. Despite hepatic Fe loading, hepcidin expression was decreased in TfR2 mutant mice compared with wild-type mice. Even when compared with Fe-loaded wild-type mice, TfR2 mutant mice had increased Fe absorption, increased duodenal Fe transport gene expression, increased liver Fe uptake, and decreased liver hepcidin expression. In conclusion, despite systemic Fe loading, Fe absorption and liver Fe uptake were increased in TfR2 mutant mice in association with decreased expression of hepcidin. These findings support a model in which TfR2 is a sensor of Fe status and regulates duodenal Fe absorption and liver Fe uptake.
PURPOSE: To study the clinical outcomes of subjects who are homozygous for the C282Y mutation of the hemochromatosis gene. SUBJECTS AND METHODS: All patients referred to a tertiary referral centre for hemochromatosis were included. The study also included 16 C282Y homozygotes detected in a population screening study. RESULTS: The study comprised 277 C282Y homozygotes, including 16 nonexpressing C282Y homozygotes. The mean follow-up period was 7.3 years (range zero to 44 years). The actuarial survival rates of C282Y homozygotes at five, 10 and 20 years were 95%, 93% and 66%, respectively. Life-threatening diseases (cirrhosis, hepatocellular carcinoma, diabetes, heart disease) were present in 36% of male C282Y homozygotes and 19% of female C282Y homozygotes. Cirrhosis of the liver and diabetes were the major clinical symptoms affecting long term survival. Only one nonexpressing homozygote required venesection therapy during the follow-up period. CONCLUSIONS: Long term survival is excellent in C282Y homozygotes diagnosed and treated before the development of cirrhosis and diabetes.
BACKGROUND: Parents of hereditary hemochromatosis (HH) homozygote patients, who are predominantly HH heterozygotes, have been found to have an increased risk of colonic neoplasia, diabetes, stroke death, stomach cancer and leukemia. The health histories of siblings of HH patients are reported. METHODS: Individuals homozygous for HH were mailed questionnaires concerning the health histories of their siblings. Spouses of the HH homozygotes were asked to complete accompanying questionnaires concerning their siblings. The frequencies of serious illness and, when specified, each reported disease were determined by zygosity, odds ratios and 95% confidence intervals estimated. RESULTS: Data were available for 279 siblings known to be HH homozygotes (HHs), and 1,265 other siblings of HH patients, who are predominantly hemochromatosis heterozygotes (HHhet). Controls consisted of 1,338 spouse siblings in whom only the general population prevalence of HH homozygosity and heterozygosity existed. Odds ratios comparing HH strata to controls were elevated for serious illness (1.12 in HHhet, 1.71 in HHs), diabetes (0.78, 2.45), arthritis (2.10, 1.69), and hepatoma (1.06, 11.96). CONCLUSIONS: There was a significant trend for increased risk of serious illness among siblings of HH patients with increasing exposure to the HH gene, especially for diabetes, arthritis and hepatoma.
Spontaneous and radiation-induced chromosome damage in cultured lymphocytes was examined in a pilot study of 11 patients with idiopathic hemochromatosis and matched controls. Increased frequencies of chromosome breaks were found in the patients, both spontaneously and after exposure to ionizing radiation, but the differences between patients and controls were not statistically significant (p greater than 0.05) when individual data were analyzed. When pooled (group) data for patients and controls were compared, significant increases in spontaneous and radiation-induced chromosome breaks were found among the patients. The results suggest that iron overload may lead to chromosome damage in idiopathic hemochromatosis.
We analyzed the clinical data and liver histology for iron overload in 74 renal allograft recipients. Twenty of the 74 patients had histological evidence of hemosiderosis. Four patients had hemochromatosis. Of the 2 noninvasive diagnostic tests the serum ferritin level was more reliable than percent saturation of transferrin in predicting the histological diagnosis of hemosiderosis. Of the 20 patients with hemosiderosis 14 died either from liver failure or concomitant sepsis. Female patients and those who received long-term dialysis had higher susceptibility for developing hemosiderosis. Of the 6 patients treated with phlebotomies, the response was good in 4 and incomplete in 2. Hemosiderosis and hemochromatosis should be considered in the differential diagnosis of posttransplant liver disease. Intermittent phlebotomies if carried out early may prevent the progression of hemosiderosis to micronodular cirrhosis.
Genetic hemochromatosis is an autosomal recessive disease characterized by increased intestinal iron absorption and consequent tissue iron overload. The hemochromatosis gene has been localized on the short arm of chromosome 6, in close proximity to the HLA locus, but has yet to be identified. Neither the gene product nor the pathogenetic defect have been characterized. Clinical manifestations vary according to the degree of iron overload, ranging from the asymptomatic state to the features of cirrhosis and hepatocellular carcinoma. Early diagnosis remains essential, since the survival of patients without established cirrhosis is comparable to that of the general population. Transferrin saturation and ferritin levels are suggestive of the diagnosis, but measurement of the hepatic iron concentration still remains the gold standard, despite the utilization of computerized tomography and magnetic resonance imaging. Routine phlebotomies constitute the principal therapeutic option, despite the recent preliminary data on oral iron chelators.
There have been some reports on the risk of developing hemosiderosis in hemodialysis patients when heavily transfused and simultaneously possessing hemochromatosis alleles (HA). We evaluated 99 patients on chronic hemodialysis estimating their serum ferritin (SF) levels, transfusion rate, and prevalence of HLA A3, B7 and B14 alleles, which are considered to be more frequent in idiopathic hemochromatosis. We analyzed the patients as a whole group and also separately as low or high transfusion groups. There was no correlation between the number of HA and the mean SF levels. The presence of HA is not a risk factor for the development of hemosiderosis when excessive transfusions and parenteral iron administration are avoided.
The distribution of lymphocyte subsets in blood, thymus, spleen, mesenteric lymph nodes, Peyer's patches and bone marrow was evaluated in an experimental model of secondary hemochromatosis in rats. The values of CD2, CD4, CD8, B and NK cells in these different lymphoid compartments did not differ between the control group and the experimental group. These results suggest that the abnormalities of lymphocyte subsets previously reported in patients with secondary hemochromatosis may be due to factors other than iron overload.
A patient with multiorgan involvement of non-iatrogenic hemochromatosis secondary to congenital dyserythropoietic anemia (CDA) type 2 is described. The clinical manifestations of hemochromatosis preceded the diagnosis of CDA. CDA should be included among the hematological disorders associated with iron overload. Iron therapy and blood transfusions should be avoided if possible in patients with CDA, and all such patients should be carefully screened for the known complications of iron overload.
Neonatal hemochromatosis is a rare inherited disorder of iron metabolism in which various tissues contain excessive amounts of iron. Only in a very few cases in which the disease is associated with fetal nonimmune hydrops is there the possibility for prenatal diagnosis. We present a case of fetal nonimmune hydrops fetalis in which severe fetal anemia and elevated liver enzymes were found. Retrospectively, according to pathological examination, these were signs of neonatal hemochromatosis. Only the knowledge of the disease entity allows antenatal diagnosis and rational perinatal management.
BACKGROUND AND PURPOSE: Serum ferritin and heterozygosity for the C282Y mutation of the hemochromatosis gene have both been associated with an increased risk of cardiovascular events. The purpose of the study was to test whether either is a risk predictor for asymptomatic carotid atherosclerosis. METHODS: We assessed carotid intima-media wall thickness (IMT) and focal plaque formation by high-resolution B-mode ultrasound, conventional risk factors, serum ferritin levels, and the C282Y mutation of the hemochromatosis gene in a randomly selected community population of 1098 subjects (545 women and 553 men) aged 27 to 77 years. RESULTS: After adjustment for conventional risk factors, serum ferritin was not associated with carotid mean IMT. Women with ferritin values over the first quartile (>34 microg/L) had an adjusted odds ratio of 2.1 (95% CI, 1. 3 to 3.4; P:=0.0016) for carotid plaque compared with the first quartile. Ferritin was not associated with carotid plaque in men. Subjects who were heterozygous for the C282Y mutation constituted 11. 4% of the population, and there was no independent association of this genotype with either carotid IMT or focal plaque formation. CONCLUSIONS: We conclude that in our community population, C282Y genotype status was not a risk predictor for either carotid mean IMT or plaque formation. Serum ferritin values in women were independently associated with carotid plaque.
BACKGROUND: We tested the hypothesis that the hereditary hemochromatosis genotypes C282Y/C282Y, C282Y/H63D, or C282Y/wild-type are risk factors for ischemic heart disease (IHD) and myocardial infarction (MI). METHODS AND RESULTS: We performed a prospective study of 9178 individuals from the Danish general population followed up for 24 years, during which 1035 and 511 developed IHD and MI, respectively, and a case-control study of 2441 and 1113 IHD and MI cases versus 8080 controls. C282Y/C282Y, C282Y/H63D, and C282Y/wild-type versus wild-type/wild-type individuals were not associated with increased risk of IHD or MI in prospective studies, overall or stratified by gender. We had 90% power to detect a hazard ratio for IHD of 3.4 for C282Y/C282Y, 1.9 for C282Y/H63D, and 1.3 for C282Y/wild-type versus wild-type/wild-type. Furthermore, these genotypes were not associated with increased risk of IHD or MI in case-control studies, overall or stratified by gender. We had 90% power to detect an odds ratio for IHD of 3.6 for C282Y/C282Y, 1.8 for C282Y/H63D, and 1.3 for C282Y/wild-type versus wild-type/wild-type. CONCLUSIONS: In these studies, hereditary hemochromatosis C282Y/C282Y, C282Y/H63D, and C282Y/wild-type genotypes were not associated with IHD or MI; however, the study lacked the power to exclude the possibility that C282Y/C282Y and C282Y/H63D individuals have a modestly increased risk of IHD or MI.
PURPOSE: Hereditary hemochromatosis is an autosomal recessive disorder of iron overload leading to oxidative stress. Mutations in HFE are responsible for approximately 90% of cases of this disease. HFE is the principal regulator of iron homeostasis, and the process involves interaction with transferrin receptor (TfR)-1, transferrin receptor (TfR)-2, and beta2-microglobulin (beta2M). Expression of HFE has not been investigated in the retina. In the present study, the expression of HFE and the HFE-interacting proteins TfR1, TfR2, and beta2M were analyzed in mouse retina. METHODS: RT-PCR was used to detect the expression of HFE mRNA in neural retina and the RPE-eyecup. Expression of HFE in intact retina was investigated by in situ hybridization, immunofluorescence, and immunogold electron microscopy. Expression of HFE-interacting proteins was also analyzed using similar techniques. RESULTS: RT-PCR showed predominant expression of HFE mRNA in the RPE-eyecup. In situ hybridization in intact retina revealed that HFE mRNA is expressed almost exclusively in RPE Immunofluorescence and immunogold electron microscopy showed that HFE protein was specifically associated with the basolateral membrane of RPE. Expression of the HFE-interacting proteins TfR1, TfR2, and beta2M was also evident in the retina. CONCLUSIONS: This is the first report on the expression of HFE in the retina. The specific localization of HFE and its interacting proteins, TfR1 and TfR2, at the basolateral membrane of RPE is relevant to the regulation of iron homeostasis in this cell. Patients with hemochromatosis may have impairment of iron homeostasis in RPE, potentially contributing to age-related RPE dysfunction and retinal degeneration.
BACKGROUND: Genetic hemochromatosis is a relatively common disease that may present as an arthropathy. In particular, arthropathy of the ankle is invariably bilateral and occurs in young men. However, the orthopaedic management of this condition has been poorly documented. METHODS: Four patients with hemochromatic ankle arthropathy were treated with unilateral mobile bearing total ankle arthroplasty. RESULTS: All four patients had good relief of symptoms after arthroplasty. CONCLUSIONS: Hemochromatosis should be considered when symmetrical ankle arthropathy occurs in a young man. Early diagnosis is necessary to prevent extra-articular progression of the disease and inappropriate management.
Transferrin receptor 2 (TfR2) is a membrane glycoprotein that mediates cellular iron uptake from holotransferrin. Homozygous mutations of this gene cause one form of hereditary hemochromatosis in humans. We recently reported that homozygous TfR2(Y245X) mutant mice, which correspond to the TfR2(Y250X) mutation in humans, showed a phenotype similar to hereditary hemochromatosis. In this study, we further analyzed the phenotype as well as iron-related gene expression in these mice by comparing the TfR2-mutant and wild-type siblings. Northern blot analyses showed that the levels of expression of hepcidin mRNA in the liver were generally lower, whereas those of duodenal DMT1, the main transporter for uptake of dietary iron, were higher in the TfR2-mutant mice as compared to the wild-type siblings. Expression of hepcidin mRNA in the TfR2 mutant mice remained low even after intraperitoneal iron loading. In isolated hepatocytes from both wild-type and TfR2 mutant mice, interleukin-6 and lipopolysaccharide each induced expression of hepcidin mRNA. These results suggest that up-regulation of hepcidin expression by inflammatory stimuli is independent of TfR2 and that TfR2 is upstream of hepcidin in the regulatory pathway of body iron homeostasis.
The gene for hemochromatosis (HFE) is expressed in a variety of cells, including those not thought to be affected by this disease. The impact of HFE on iron transport was examined in B-lymphoid cell lines developed from a patient with hemochromatosis with the HFE C282Y mutation (C282Y cells) and an individual with the wild-type HFE gene (WT cells). Whereas both cell lines expressed HFE protein, C282Y cells displayed less HFE protein at the cell surface. Transferrin receptor (TfR) number was 2- to 3-fold greater in WT cells than in C282Y cells, while TfR affinity for transferrin (Tf) was slightly lower in C282Y cells. TfR distribution between intracellular and cell-surface compartments was similar in both cell lines. Iron uptake per cell was greater in WT cells but was not increased proportional to TfR number. When considered relative to cell-surface TfR number, however, iron uptake and Tf internalization were actually greater in C282Y cells. Surprisingly, Tf-independent iron uptake was also significantly greater in C282Y cells than in WT cells. The ferritin content of C282Y cells was approximately 40% that of WT cells. Exposure of cells to pro-oxidant conditions in culture led to a greater inhibition of proliferation in C282Y cells than in WT cells. Our results indicate that in this B-lymphoid cell line, the HFE C282Y mutation affects both Tf-dependent and -independent iron uptake and enhances cell sensitivity to oxidative stress. The role of HFE in iron uptake by B cells may extend beyond its known interaction with the TfR.
We studied the effect of iron depletion on reproductive function in a 37-yr-old man with hypogonadotropic hypogonadism due to idiopathic hemochromatosis. Before therapy, he was impotent and had no libido, and seminal fluid analysis revealed no spermatozoa. Testicular biopsy showed marked impairment of spermatogenesis, but no iron load deposits. Sixteen months after institution of aggressive phlebotomy therapy, serum LH, FSH, and testosterone were normal, and potency and libido had returned. Twenty months after diagnosis the patient fathered another child. Seminal fluid analysis at that time revealed an average of 65 million spermatozoa/mL. Thus, recovery of reproductive function, documented by hormone measurements, testicular biopsy, and semen analysis, was complete. We conclude that phlebotomy alone may be adequate treatment for hypogonadotropic hypogonadism in men with hemochromatosis.