0
selected
-
1.
Iron and the liver.
Pietrangelo, A
Liver international : official journal of the International Association for the Study of the Liver. 2016;:116-23
Abstract
Humans have evolved to retain iron in the body and are exposed to a high risk of iron overload and iron-related toxicity. Excess iron in the blood, in the absence of increased erythropoietic needs, can saturate the buffering capacity of serum transferrin and result in non-transferrin-bound highly reactive forms of iron that can cause damage, as well as promote fibrogenesis and carcinogenesis in the parenchymatous organs. A number of hereditary or acquired diseases are associated with systemic or local iron deposition or iron misdistribution in organs or cells. Two of these, the HFE- and non-HFE hemochromatosis syndromes represent the paradigms of genetic iron overload. They share common clinical features and the same pathogenic basis, in particular, a lack of synthesis or activity of hepcidin, the iron hormone. Before hepcidin was discovered, the liver was simply regarded as the main site of iron storage and, as such, the main target of iron toxicity. Now, as the main source of hepcidin, it appears that the loss of the hepcidin-producing liver mass or genetic and acquired factors that repress hepcidin synthesis in the liver may also lead to iron overload. Usually, there is low-grade excess iron which, through oxidative stress, is sufficient to worsen the course of the underlying liver disease or other chronic diseases that are apparently unrelated to iron, such as chronic metabolic and cardiovascular diseases. In the future, modulation of hepcidin synthesis and activity or hepcidin hormone-replacing strategies may become therapeutic options to cure iron-related disorders.
-
2.
HFE genotype and iron metabolism in Chinese patients with myelodysplastic syndromes and aplastic anemia.
Nie, L, Li, L, Yang, L, Zhang, Y, Xiao, Z
Annals of hematology. 2010;(12):1249-53
Abstract
The incidence of HFE gene mutations in myelodysplastic syndrome (MDS) cases remains controversial. In this study, we examined the HFE C282Y and H63D mutations in 271 Chinese patients with MDS, 402 with aplastic anemia (AA) and 1,615 healthy controls by polymerase chain reaction-restriction fragment length polymorphism in combination with DNA sequencing. No C282Y mutations were observed in the entire cohort. The distribution of H63D heterozygous and homozygous genotypes was not significantly different between the AA cases and the controls (9.7% versus 10.2%, 0.25% versus 0.24%, respectively). While the H63D heterozygous genotype in MDS patients was significantly lower than that in the controls (4.1% versus 10.2%, pā=ā0.002), the H63D homozygous genotype was not detected in the MDS patients. The results suggest that HFE gene mutations are not common genetic factors in Chinese patients with MDS and AA. We also compared iron metabolic parameters, including serum ferritin, serum iron, and transferrin saturation values, between HFE mutant and HFE wild-type groups in the absence of transfusion iron overload, but no significant difference was found in either MDS or AA patients except that the level of serum iron in AA patients was significantly higher in mutant carriers than in those with wild-type HFE (pā=ā0.011). Similarly, there was no significant difference between HFE mutant and HFE wild-type MDS and AA patients in clinical indices such as alanine aminotransferase, aspartate aminotransferase, fasting blood sugar values, and electrocardiogram. The results suggest that H63D mutations may not have clinical significance in Chinese patients with MDS and AA.
-
3.
[Study on HFE gene mutations in patients with myelodysplastic syndromes and aplastic anemia].
Nie, L, Ai, XF, Zheng, YZ, Li, QH, Yang, L, Xiao, ZJ
Zhonghua xue ye xue za zhi = Zhonghua xueyexue zazhi. 2009;(4):223-8
Abstract
OBJECTIVE To detect the incidence of the HFE gene C282Y and H63D mutations in patients with myelodysplastic syndromes (MDS) and aplastic anemia (AA), and analyze the relationship of these mutations with iron metabolism, and organs impairment from iron overload. METHODS The incidence of the C282Y and H63D mutations in 271 MDS, 402 AA patients and 1615 normal subjects was measured by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) combining with DNA sequencing. Iron metabolism parameters and iron overload indices were retrospectively compared between HFE gene mutation and unmutation groups in MDS and AA patients with no transfusion history. RESULTS No C282Y and C282Y/H63D compound mutation was detected in all the three groups. The incidence of H63D heterozygous and homozygous genotype did not significantly differ between AA cases and controls (9.7% vs 10.2%, 0.25% vs 0.24% respectively, both P > 0.05). The frequency of H63D heterozygous genotype in MDS patients was significantly lower than that in controls (4.1% vs 10.2%, P = 0.002). H63D homozygous was not found in MDS patients. In both MDS and AA patients with no RBC transfusion history, serum ferritin (SF), transferrin saturation value (TS), serum iron concentration (SI) were close to or higher than normal; and unsaturated iron-binding capacity (UIBC) value was significantly lower. There was no significant difference in SF, SI, TS values between HFE-mutation and -unmutation MDS patients. For AA patients, only the level of SI was significantly higher in HFE-mutant group than in -unmutation group [42.6 (24.6-60.4) micromol/L vs 32.0 (8.4-63.3) micromol/L, P = 0.011]. There was no significant difference in the values of liver enzyme, fasting blood sugar (FBS), abnormal electrocardiogram (ECG), peripheral blood indices between HFE-mutation and -unmutation MDS and AA groups (all P > 0.05). CONCLUSION The distribution of C282Y and H63D mutations has ethnic and genetic disparity, the frequency in Chinese population is lower than that in Caucasian. It seems that MDS and AA patients are susceptible to iron overload, in the diseases itself and the mutations of HFE gene are not the major factor for iron overload in the patients.
-
4.
Hereditary hemochromatosis.
Fix, OK, Kowdley, KV
Minerva medica. 2008;(6):605-17
Abstract
Hereditary hemochromatosis (HH) refers to several inherited disorders of iron metabolism leading to tissue iron overload. Classical HH is associated with mutations in HFE (C282Y homozygotes or C282Y/H63D compound heterozygotes) and is almost exclusively found in populations of northern European descent. Non-HFE associated HH is caused by mutations in other recently identified genes involved in iron metabolism. Hepcidin is an iron regulatory hormone that inhibits ferroportin-mediated iron export from enterocytes and macrophages. Defective hepcidin gene expression or function may underlie most forms of HH. Target organs and tissues affected by HH include the liver, heart, pancreas, joints, and skin, with cirrhosis and diabetes mellitus representing late signs of disease in patients with markedly elevated liver iron concentration. Compound heterozygotes have milder disease than C282Y homozygotes and clinical signs of HH in these patients are usually associated with other factors such as alcoholism and the dysmetabolic syndrome. The most frequent causes of death in HH are liver cancer, cirrhosis, cardiomyopathy, and diabetes, but patients who undergo successful iron depletion before the development of cirrhosis or diabetes can have normal survival. Classical HH is characterized by incomplete penetrance and variable expressivity, and women are less affected than men by iron overload and iron overload-related disease. The diagnosis of HH is established by genetic testing in patients with elevated transferrin saturation values. Patients with an established diagnosis of HH and iron overload should be treated with phlebotomy to achieve body iron depletion followed by maintenance phlebotomy. Population screening for HH is controversial principally because of incomplete penetrance, but screening of selected, high risk populations and first-degree relatives of affected probands may be cost effective.
-
5.
[Hereditary haemochromatosis: novel genes, novel diseases and hepcidin].
Bergmans, JP, Kemna, EH, Janssen, MC, Jacobs, EM, Stalenhoef, AF, Marx, JJ, Swinkels, DW
Nederlands tijdschrift voor geneeskunde. 2007;(20):1121-7
Abstract
Since the discovery of the HFE gene of hereditary haemochromatosis in 1996 several new genetic defects have been identified, enabling explanation of the cause and variety of this disease. To date, at least 5 major types of hereditary haemochromatosis have been recognised. All these genes encode for proteins that are involved in metabolic pathways relevant to hepcidin synthesis in the liver. Hepcidin is a small protein that regulates the activity of the iron exporting protein ferroportin in the basolateral membrane of duodenal cells and the cell membrane of macrophages and thereby controls serum iron concentration. Plasma hepcidin concentration is elevated in body iron excess and by inflammatory stimuli, and is lowered in erythroid iron demand, hypoxia and most types of hereditary haemochromatosis. It is the clinician's task to diagnose hereditary haemochromatosis before irreversible tissue damage arises and at the same time to differentiate between ongoing iron accumulation and increasingly prevalent disorders with elevated serum ferritin such as the metabolic syndrome.
-
6.
Non-HFE hemochromatosis: genetics, pathogenesis, and clinical management.
Nelson, JE, Kowdley, KV
Current gastroenterology reports. 2005;(1):71-80
Abstract
Recent advances in our understanding of iron metabolism and the epidemiology of iron overload disorders have shown that hereditary forms of hemochromatosis can result from mutations in several iron metabolism genes other than HFE, including Hamp, HJV, TFR2, and SCL40A. These "non-HFE" forms of hemochromatosis are much rarer than HFE-related hemochromatosis but exhibit a similar phenotype, and with the exception of ferroportin disease, a similar pattern of inheritance and parenchymal iron accumulation. Therefore, these diseases can be thought of as variant forms of a primary hepatic iron overload syndrome; thus, a unified approach can be used for evaluation and diagnosis. Management generally consists of periodic phlebotomies until iron is depleted.