UNIPROT:P02794 - FACTA Search

Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Target Concepts:

Query: UNIPROT:P02794 (ferritin)
17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Early erroneous diagnosis of rheumatic disease is common in subjects with arthropathy due to hereditary hemochromatosis. A 71-year-old male with chronic obstructive pulmonary disease and monoclonal gammopathy underwent hip replacement and was referred to our Department because of altered liver function tests. Test results were negative for hepatitis B surface antigen and hepatitis C virus, and positive for rheumatoid factor. A diagnosis of rheumatoid arthritis had been made on the basis of compatible joint involvement and laboratory data and steroid treatment prescribed. Since his serum ferritin was 3249 ng/mL, genetic testing for hereditary hemochromatosis was carried out and revealed homozygosity for Cys282Tyr mutation in the HFE gene. Liver biopsy disclosed cirrhosis compatible with hemochromatosis. Following a review of the patients' radiographs, the diagnosis of hemochromatosis arthropathy was made. Phlebotomies and family screening for hereditary hemochromatosis were done. The most logical explanation for the positive rheumatoid factor result in this subject are his age and the presence of two chronic diseases involving long-standing antigenic stimulation and monoclonal gammopathy of uncertain significance. It is important to distinguish rheumatoid arthritis from hemochromatosis arthropathy for several reasons: patients with hereditary hemochromatosis do not require corticosteroid treatment; in case of erroneous diagnosis of rheumatoid arthritis, phlebotomy is not started early, and familial genetic counseling is not considered. In male subjects with positive rheumatoid factor and joint and liver disease, hereditary hemochromatosis should be considered. More liberal use of genetic testing is justified in such cases.
...
PMID:Hereditary hemochromatosis masquerading as rheumatoid arthritis. 1168 50

This review examines the clinical consequences for the practicing hematologist of remarkable new insights into the pathophysiology of disorders of iron and heme metabolism. The familiar proteins of iron transport and storage-transferrin, transferrin receptor, and ferritin-have recently been joined by a host of newly identified proteins that play critical roles in the molecular management of iron homeostasis. These include the iron-regulatory proteins (IRP-1 and -2), HFE (the product of the HFE gene that is mutated in most patients with hereditary hemochromatosis), the divalent metal transporter (DMT1), transferrin receptor 2, ceruloplasmin, hephaestin, the "Stimulator of Fe Transport" (SFT), frataxin, ferroportin 1 and others. The growing appreciation of the roles of these newly identified proteins has fundamental implications for the clinical understanding and laboratory evaluation of iron metabolism and its alterations with iron deficiency, iron overload, infection, and inflammation. In Section I, Dr. Brittenham summarizes current concepts of body and cellular iron supply and storage and reviews new means of evaluating the full range of body iron stores including genetic testing for mutations in the HFE gene, measurement of serum ferritin iron, transferrin receptor, reticulocyte hemoglobin content and measurement of tissue iron by computed tomography, magnetic resonance imaging and magnetic susceptometry using superconducting quantum interference device (SQUID) instrumentation. In Section II, Dr. Weiss discusses the improved understanding of the molecular mechanisms underlying alterations in iron metabolism due to chronic inflammatory disorders. The anemia of chronic disorders remains the most common form of anemia found in hospitalized patients. The network of interactions that link iron metabolism with cellular immune effector functions involving pro- and anti-inflammatory cytokines, acute phase proteins and oxidative stress is described, with an emphasis on the implications for clinical practice. In Section III, Dr. Brissot and colleagues discuss how the diagnosis and management of hereditary hemochromatosis has changed following the identification of the gene, HFE, that is mutated in most patients with hereditary hemochromatosis, and the subsequent development of a genotypic test. The current understanding of the molecular effects of HFE mutations, the usefulness of genotypic and phenotypic approaches to screening and diagnosis and recommendations for management are summarized.
...
PMID:Clinical Consequences of New Insights in the Pathophysiology of Disorders of Iron and Heme Metabolism. 1170 34

The protein defective in hereditary hemochromatosis, called HFE, is similar to MHC class I-type proteins and associates with beta2-microglobulin (beta2M). Its association with beta2M was previously shown to be necessary for its stability, normal intracellular processing, and cell surface expression in transfected COS cells. Here we use stably transfected Chinese hamster ovary cell lines expressing both HFE and beta2M or HFE alone to study the effects of beta2M on the stability and maturation of the HFE protein and on the role of HFE in transferrin receptor 1 (TfR1)-mediated iron uptake. In agreement with prior studies on other cell lines, we found that overexpression of HFE, without overexpressing beta2M, resulted in a decrease in TfR1dependent iron uptake and in lower iron levels in the cells, as evidenced by ferritin and TfR1 levels measured at steady state. However, overexpression of both HFE and beta2M had the reverse effect and resulted in an increase in TfR1-dependent iron uptake and increased iron levels in the cells. The HFE-beta2M complex did not affect the affinity of TfR1 for transferrin or the internalization rate of transferrin-bound TfR1. Instead, HFE-beta2M enhanced the rate of recycling of TfR1 and resulted in an increase in the steady-state level of TfR1 at the cell surface of stably transfected cells. We propose that Chinese hamster ovary cells provide a model to explain the effect of the HFE-beta2M complex in duodenal crypt cells, where the HFE-beta2M complex appears to facilitate the uptake of transferrin-bound iron to sense the level of body iron stores. Impairment of this process in duodenal crypt cells leads them to be iron poor and to signal the differentiating enterocytes to take up iron excessively after they mature into villus cells in the duodenum of hereditary hemochromatosis patients.
...
PMID:Regulation of transferrin-mediated iron uptake by HFE, the protein defective in hereditary hemochromatosis. 1186 20

The vast majority of Caucasian patients presenting with hereditary hemochromatosis demonstrate a single homozygous missense mutation in the HFE gene (C282Y). The underlying genetic defects in hemochromatosis patients of non-Caucasian origin are largely unknown. A 48-year-old man of Vietnamese origin presented with insulin-dependent diabetes mellitus, tertiary adrenocortical insufficiency, and laboratory results highly indicative of hereditary hemochromatosis. Because the patient was negative for the known HFE gene mutations C282Y, H63D, and S65C HFE, the entire coding region and intron/exon boundaries of the HFE gene was investigated. Sequencing studies identified a homozygous G-to-A transition at position +1 of intron 5 (IVS5+1 G/A). This newly described mutation alters the invariant G at position +1 of the 5' splice site causing altered mRNA splicing and exon skipping with exon 4 being spliced to exon 6. Both heterozygously affected children (age 19 and 20 years) had moderately increased ferritin levels with normal serum iron concentration and transferrin saturation. The newly described mutation was not detected in a control group consisting of 220 Caucasian individuals as verified by allele-specific polymerase chain reaction. We describe for the first time a homozygous HFE splice site mutation (IVS5+1 G/A) in a non-Caucasian patient with hereditary hemochromatosis. Although the absence of this novel HFE gene mutation in Caucasian subjects suggests that the mutation is exclusive to this family, mutation screening in populations of different ethnic background is recommended to precisely define its contribution to hereditary hemochromatosis in non-Caucasian patients.
...
PMID:A homozygous HFE gene splice site mutation (IVS5+1 G/A) in a hereditary hemochromatosis patient of Vietnamese origin. 1187 12

The hemochromatosis gene, HFE, is located on chromosome 6 in close proximity to the HLA-A locus. Most Caucasian patients with hereditary hemochromatosis (HH) are homozygous for HLA-A3 and for the C282Y mutation of the HFE gene, while a minority are compound heterozygotes for C282Y and H63D. The prevalence of these mutations in non-Caucasian patients with HH is lower than expected. The objective of the present study was to evaluate the frequencies of HLA-A antigens and the C282Y and H63D mutations of the HFE gene in Brazilian patients with HH and to compare clinical and laboratory profiles of C282Y-positive and -negative patients with HH. The frequencies of HLA-A and C282Y and H63D mutations were determined by PCR-based methods in 15 male patients (median age 44 (20-72) years) with HH. Eight patients (53%) were homozygous and one (7%) was heterozygous for the C282Y mutation. None had compound heterozygosity for C282Y and H63D mutations. All but three C282Y homozygotes were positive for HLA-A3 and three other patients without C282Y were shown to be either heterozygous (N = 2) or homozygous (N = 1) for HLA-A3. Patients homozygous for the C282Y mutation had higher ferritin levels and lower age at onset, but the difference was not significant. The presence of C282Y homozygosity in roughly half of the Brazilian patients with HH, together with the findings of HLA-A homozygosity in C282Y-negative subjects, suggest that other mutations in the HFE gene or in other genes involved in iron homeostasis might also be linked to HH in Brazil.
...
PMID:Analysis of HLA-A antigens and C282Y and H63D mutations of the HFE gene in Brazilian patients with hemochromatosis. 1188 10

A patient with clinically manifest hereditary hemochromatosis was found to be heterozygous for the c.845 A-->G (C282Y) mutation. As simple heterozygotes for this mutation do not develop the hemochromatosis phenotype, the coding region of the patient's HFE gene was sequenced and a previously undescribed nonsense mutation was identified at c.211 C-->T (R74X). The patient's brother who also had the hemochromatosis phenotype shared his HFE genotype. To determine how common such mutations might be, the coding and 5' region of the HFE genes of 11 subjects who had been found in a large population survey to be heterozygous for the C282Y mutation and had elevated ferritin levels were sequenced. No mutations were found. Sequencing of the HFE gene also revealed two polymorphisms that had not previously been noted, -467 C-->G and -970 T-->G. Neither of these mutations appear to cause an abnormality in iron metabolism.
...
PMID:A previously undescribed nonsense mutation of the HFE gene. 1190 54

Iron-related insulin-resistance is improved by iron depletion or treatment with iron chelators. The aim of this study was to evaluate insulin sensitivity and insulin secretion after blood letting in patients who had high-ferritin type 2 diabetes and were randomized to blood letting (three phlebotomies [500 ml of blood] at 2-week intervals, group 1) or to observation (group 2). Insulin secretion and sensitivity were tested at baseline and 4 and 12 months thereafter. The two groups were matched for age, BMI, pharmacologic treatment, and chronic diabetic complications. All patients were negative for C282Y mutation of hereditary hemochromatosis. Baseline glycated hemoglobin (6.27 +/- 0.9% vs. 6.39 +/- 1.2%), insulin sensitivity (2.75 +/- 1.8 vs. 3.2 +/- 2.1 mg.dl(-1).min(-1)), and area under the curve for C-peptide (AUC(C-peptide); 38.7 +/- 11.6 vs. 37.6 +/- 14.1 ng.ml(-1).min(-1)) were not significantly different between the two groups of patients. Body weight, blood pressure, blood hematocrit levels, and drug treatment remained essentially unchanged during the study period. As expected, serum ferritin, transferrin saturation index, and blood hemoglobin decreased significantly at 4 months only in patients who received blood letting. In parallel to this changes, blood HbA(1c) decreased significantly only in group 1 subjects (mean differences, -0.61; 95% CI, -0.17 to -1.048; P = 0.01). AUC(C-peptide) decreased by -10.2 +/- 6.3% after blood letting. In contrast, a 10.4 +/- 6.4% increase in AUC(C-peptide) was noted in group 2 subjects at 4 months (P = 0.032). At 12 months, AUC(C-peptide) returned to values not significantly different from baseline in the two groups of subjects. At 4 months, the change in insulin sensitivity from baseline was significantly different between the two groups (80.6 +/- 43.2% vs. -8.6 +/- 9.9% in groups 1 and 2, respectively, P = 0.049). At 12 months, the differences between the two groups were even more marked (55.5 +/- 24.8% vs. -26.8 +/- 9.9%; P = 0.005). When the analysis was restricted to those subjects who completed the follow-up until 12 months, results did not show differences compared with the changes observed at 4 months, except for insulin sensitivity. A statistically significant increase in insulin sensitivity was observed in the blood-letting group (from 2.30 +/- 1.81 to 3.08 +/- 2.55 mg.dl(-1).min(-1) at 4 months, to 3.16 +/- 1.85 mg.dl(-1).min(-1) at 12 months; P = 0,045) in contrast with group 2 subjects (from 3.24 +/- 1.9 to 3.26 +/- 2.05 mg.dl(-1).min(-1) at 4 months, to 2.31 +/- 1.35 mg.dl(-1).min(-1) at 12 months). In summary, blood letting led simultaneously to decreased blood HbA(1c) levels and to changes in insulin secretion and insulin resistance that were significantly different from those observed in a matched observational group of subjects with high-ferritin type 2 diabetes. The mechanisms for improvement in peripheral insulin sensitivity after blood letting should be investigated further.
...
PMID:Blood letting in high-ferritin type 2 diabetes: effects on insulin sensitivity and beta-cell function. 1191 18

Since transferrin was discovered more than half a century ago, a considerable effort has been made towards understanding tranferrin-mediated iron uptake. However, it was not until recently with the identification and characterization of several new genes related to iron homeostasis, such as the hemochromatosis protein HFE and the iron transporter DMT1, that our knowledge has been advanced dramatically. A major pathway for cellular iron uptake is through internalization of the complex of iron-bound transferrin and the transferrin receptor, which is negatively modulated by HFE, a protein related to hereditary hemochromatosis. Iron is released from transferrin as the result of the acidic pH in endosome and then is transported to the cytosol by DMT1. The iron is then utilized as a cofactor by heme and ribonucleotide reductase or stored in ferritin. Apart from iron, many other metal ions of therapeutic and diagnostic interests can also bind to transferrin at the iron sites and their transferrin complexes can be recognized by many cells. Therefore, transferrin has been thought as a "delivery system" for many beneficial and harmful metal ions into the cells. Transferrin has also be widely applied as a targeting ligand in the active targeting of anticancer agents, proteins, and genes to primary proliferating malignant cells that overexpress transferrin receptors. This is achieved by conjugation of transferrin with drugs, proteins, hybride systems with marcomolecules and as liposomal-coated systems. Conjugates of anticancer drugs with transferrin can significantly improve the selectivity and toxicity and overcome drug resistance, thereby leading to a better treatment. The coupling of DNA to transferrin via a polycation such as polylysine or via cationic liposomes can target and transfer of the extrogenous DNA particularly into proliferating cells through receptor-mediated endocytosis. These kinds of non-viral vectors are potential alternatives to viral vectors for gene therapy, if the transfection efficiency can be improved. Moreover, transferrin receptors have shown potentials in delivery of therapeutic drugs or genes into the brain across blood-brain barrier.
...
PMID:Transferrin/transferrin receptor-mediated drug delivery. 1193 19

Aims of the study were: (i) to determine the prevalence of mutations C282Y and H63D in the HFE gene causing hereditary hemochromatosis in patients with type 2 diabetes mellitus and non-diabetics, (ii) to investigate the relationship among HFE genotypes, serum ferritin and glucose intolerance and (iii) to assess possible association of HFE mutations with the susceptibility to develop late diabetic complications in the Czech population. Two approaches were employed - the case-control study comprising diabetics and non-diabetic controls (n = 326) and the cross-sectional study comprising subjects with a previously unknown defect of glucose tolerance (n = 113, oral glucose tolerance test performed in each subject). Allele frequencies of C282Y and H63D did not differ between diabetic and control groups nor among subjects with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and diabetes. Ferritin levels significantly differed between diabetic and non-diabetic women (P<1.10 (-3)) and among subjects with NGT, IGT and diabetes (P<0.05). Differences in ferritin levels related to particular genotypes of C282Y and H63D were not detected. Prevalence of diabetes in the first and second quartiles of ferritin distribution differed highly significantly from the prevalence in the third and fourth quartiles in women (P = 0.000037), OR = 3.50 (95% CI, 1.89-6.48). The extent of diabetic late complications did not correlate with ferritin plasma levels.
...
PMID:Relations among serum ferritin, C282Y and H63D mutations in the HFE gene and type 2 diabetes mellitus in the Czech population. 1214 86

Hereditary hemochromatosis is an inherited autosomal recessive disease, associated to a mutation in the recently described HFE gene, which is located on the short arm of chromosome 6. The product of this gene combines with the beta-2-microglobulin and the ferritin receptor, and regulates the iron absorption in the small intestine crypt cells. It is possible that the mutation may cause the increased iron uptake by the intestinal cells. The disease is very much common in men after the forties, and its expression is influenced by concomitant alcoholism, iron rich diet, oral and parenteral iron administration, menstrual blood loss or abnormal hemorrhages, blood donations, pregnancy, lactation, and iron malabsorption clinical conditions, like celiac disease. Many patients are asymptomatic, and the diagnosis may be suspected by hepatomegaly of unknown cause, abnormal iron metabolism tests, increased serum aminotransferase levels, diabetes mellitus, and anonymous arthropathy. Less commonly hereditary hemochromatosis presented by symptoms and signs of chronic liver disease, or by the classic triad described by Trousseau skin pigmentation, hepatomegaly and diabetes mellitus. The diagnosis is confirmed by the increased serum ferritin levels and transferrin saturation, and the stainable iron in hepatocytes, measured by scale devised by Scheuer et al, or the measurement of the hepatic iron. The C282Y mutation was found in 64 to 100% of patients; eventually, subjects with hepatic iron overload identical to hereditary hemochromatosis has no mutation, and homozygous for the C282Y mutation do not express iron overload. Iron is best and quickly removed by weekly or twice-weekly phlebotomy of 500 ml, containing approximately 250 mg iron. One to 3 years of weekly phlebotomy may be required to reduce stores to normal. As a guide to long-term maintenance therapy, is recommended phlebotomy every 3 months and the serum ferritin level should be maintained by less than 50 ng/ml.
...
PMID:[Hereditary hemochromatosis]. 1217 Feb 86

<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>