Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Genetic hemochromatosis is an autosomal recessive disease, characterized by an increased iron absorption, leading to progressive iron overload. The fully expressed phenotype comprises fatigue, skin pigmentation, liver disease with hepatomegaly, cirrhosis and hepatocellular carcinoma, and diabetes. Arthralgias are frequent, cardiopathy or impotence may occur. This presentation is now unfrequent with earlier diagnosis, and patients are often asymptomatic--with only biochemical expression--or pauci-symptomatic (mild fatigue, arthralgias or increased transaminases). Transferrin saturation is always increased. Serum ferritin is proportional to iron burden. Diagnosis is now easy, since most patients are homozygote for the C282Y mutation of the HFE gene. Liver biopsy can be useful to quantify iron overload and assess liver fibrosis. The disease can be lethal due to liver disease, carcinoma or heart disease, but life expectancy goes to normal if patients are treated before the occurrence of cirrhosis. Treatment relies on regular venesections. Familial screening is essential.
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PMID:[Diagnosis and treatment of genetic hemochromatosis]. 1086 97

Juvenile hemochromatosis is a rare genetic disorder that causes iron overload. Clinical complications, which include liver cirrhosis, heart failure, hypogonadotropic hypogonadism and diabetes, appear earlier and are more severe than in HFE-related hemochromatosis. This disorder, therefore, requires an aggressive therapeutic approach to achieve iron depletion. We report here the case of a young Italian female with juvenile hemochromatosis who was unable to tolerate frequent phlebotomy because of coexistent ss-thalassemia trait. The patient was successfully iron-depleted by combining phlebotomy with recombinant human erythropoietin.
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PMID:Juvenile hemochromatosis associated with B-thalassemia treated by phlebotomy and recombinant human erythropoietin. 1094 34

Genetic testing for the C282Y mutation of the HFE gene has been a major advance in the diagnosis of hereditary hemochromatosis. In most studies, more than 90% of typical hemochromatosis patients are homozygous for the C282Y mutation. Large-scale population screening studies in predominantly Caucasian populations have demonstrated a high prevalence of C282Y homozygotes of approximately 1 in 300. Despite this high prevalence by genetic testing, the clinical diagnosis of hemochromatosis and mortality from the disease are much less common. One possibility is the presence of many undiagnosed cases with nonspecific symptoms, and deaths occurring that are attributed to liver disease, diabetes, and heart disease without the recognition of iron overload secondary to hemochromatosis. Another possibility is a high prevalence of nonexpressing homozygotes. In this review, the available data on nonexpressing C282Y homozygotes is collected including information on pathogenesis, environmental interactions, and implications for population screening using genetic testing.
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PMID:Nonexpressing homozygotes for C282Y hemochromatosis: minority or majority of cases? 1100

Hemochromatosis is one of the most frequent genetic diseases among the white populations, affecting one in three hundred persons. Its diagnosis has been radically transformed by the discovery of the HFE gene. In a given individual, the diagnosis can, from now on, be ascertained on the sole association of a plasma transferrin saturation (TS) over 45% and homozygosity for the C282Y mutation. Liver biopsy is only required to search for cirrhosis whenever there is hepatomegaly and/or serum ferritin >1000 ng/ml and/or elevated serum AST. Family screening is mandatory, primarily centered on the siblings. The treatment remains based on venesection therapy which improves many features of the disease (one of the most refractory, however, being the joint signs) and permits normal life expectancy provided the diagnosis is established prior to the development of cirrhosis or of insulin-dependent diabetes. In view of the prevalence, the non-invasive diagnosis, the spontaneous severity and the efficacy of a very simple therapy, hemochromatosis should benefit from population screening. This screening could be based, first, on the assessment of transferrin saturation, followed - when elevated - by the search for the C282Y mutation. The discovery of the HFE gene has also paved the road for the individualization of other types of iron overload syndromes which are not HFE-related.
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PMID:Clinical aspects of hemochromatosis. 1109 95

Hereditary hemochromatosis (HHC) is an inherited disorder of iron metabolism affecting approximately 1 in 200-300 individuals of Northern European descent. Over time, the continued deposition of iron in parenchymal cells of many organs can eventually lead to diabetes mellitus, cardiomyopathy, and hepatic cirrhosis, the last of which is frequently followed by hepatocellular carcinoma. Although the complications of HHC can be devastating, its clinical management is simple and effective if the disease is identified early in its progression. The recent elucidation of the HFE gene has provided insight into the pathogenesis of HHC and provided a means for the early identification of individuals in whom HHC may develop. Two mutations have been implicated in HHC: C282Y and H63D. The former occurs in a homozygous state seen in 75-100% of patients with HHC. The high correlation of HFE to HHC has caused it to be considered as a candidate gene for population-based genetic testing for diagnosis and detection of predisposition to HHC. In addition, mechanisms of iron transport and metabolism are unfolding and are providing clues to the enigma of iron homeostasis and the pathophysiology of iron overload.
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PMID:What's new in hemochromatosis. 1122 84

Increased iron stores may play a role in the development of coronary heart disease (CHD) by increasing lipoprotein oxidation. Recently, mutations have been discovered in the gene (HFE) for hereditary hemochromatosis, an autosomal recessive condition of disordered iron metabolism, absorption, and storage. It is possible that people who carry HFE mutations have increased risk of CHD. We used a prospective case-cohort design (243 CHD cases and 535 non-cases) to determine whether the HFE C282Y mutation was associated with incident CHD in a population-based sample of middle-aged men and women. The frequencies of homozygosity and heterozygosity for the C282Y mutation in the ARIC study population were 0.2% (one homozygous person) and 6%, respectively. The C282Y mutation was associated with nonsignificantly increased risk of CHD (relative risk=1.60, 95% CI 0.9-2.9). After adjusting for other confounding risk factors (age, race, gender, ARIC community, smoking status, diabetes status, hypertension status, LDL cholesterol, HDL cholesterol, and triglycerides), the association became stronger (relative risk=2.70, 95% CI 1.2-6.1). However, a sensitivity analysis showed that this estimate of relative risk was somewhat unstable due to few subjects in some strata. Our prospective findings suggest that individuals carrying the HFE C282Y mutation may be at increased risk of CHD.
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PMID:A prospective study of coronary heart disease and the hemochromatosis gene (HFE) C282Y mutation: the Atherosclerosis Risk in Communities (ARIC) study. 1125 77

Like most essential nutrients, Fe needs to be maintained in the body at a defined level for optimal health, with appropriate adaptation to varying Fe needs and supply. The primary mechanism for controlling Fe level is the regulation of Fe absorption. Several different proteins have been identified as contributors to the process. Despite a complex regulatory system, Fe disorders (both Fe deficiency and Fe overload) occur. Fe deficiency is a common problem worldwide, resulting from inadequate dietary Fe and blood loss. Complications include pre-term labour, developmental delay, and impaired work efficiency. No specific genetic syndromes causing isolated Fe deficiency have been described, but animal studies and clinical observations suggest that such a relationship may be a possibility. Conversely, the known causes of Fe overload are genetic. Fe overload is less common than Fe deficiency, but can result in serious medical complications, including cirrhosis, primary liver cancer, diabetes, cardiomyopathy and arthritis. The most common and best characterized syndrome of Fe overload is hereditary haemochromatosis (HHC), an autosomal recessive disorder. Mutations in the HFE protein cause HHC, but the clinical presentation is variable. Of particular interest is the factor that some FIFE genotypes appear to be associated with protection from Fe deficiency. Other genetic variants in the regulatory pathway may influence the likelihood of Fe deficiency and Fe overload. Studies of genetic variants in HFE and other regulatory proteins provide important tools for studying the biological processes in Fe regulation. This work is likely to lead to new insights into Fe disorders and potentially to new therapeutic approaches. It will not be complete, however, until coordinated study of both genetic and nutritional factors is undertaken.
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PMID:Iron deficiency and iron overload: effects of diet and genes. 1131 Apr 26

Insulin sensitivity (euglycemic clamp, insulin infusion rate: 40 mU. m(-2). min(-1)) was studied in 30 subjects with biopsy-proven nonalcoholic fatty liver disease (NAFLD), normal glucose tolerance, and a BMI <30 kg/m(2). Of those 30 subjects, 9 had pure fatty liver and 21 had evidence of steatohepatitis. In addition, 10 patients with type 2 diabetes under good metabolic control and 10 healthy subjects were studied. Most NAFLD patients had central fat accumulation, increased triglycerides and uric acid, and low HDL cholesterol, irrespective of BMI. Glucose disposal during the clamp was reduced by nearly 50% in NAFLD patients, as well as in patients with normal body weight, to an extent similar to that of the type 2 diabetic patients. Basal free fatty acids were increased, whereas insulin-mediated suppression of lipolysis was less effective (-69% in NAFLD vs. -84% in control subjects; P = 0.003). Postabsorptive hepatic glucose production (HGP), measured by [6,6-(2)H(2)]glucose, was normal. In response to insulin infusion, HGP decreased by only 63% of basal in NAFLD vs. 84% in control subjects (P = 0.002). Compared with type 2 diabetic patients, NAFLD patients were characterized by lower basal HGP, but with similarly reduced insulin-mediated suppression of HGP. There was laboratory evidence of iron overload in many NAFLD patients, but clinical, histological, and biochemical data (including insulin sensitivity) were not correlated with iron status. Four subjects were heterozygous for mutation His63Asp of the HFE gene of familiar hemochromatosis. We concluded that NAFLD, in the presence of normoglycemia and normal or moderately increased body weight, is characterized by clinical and laboratory data similar to those found in diabetes and obesity. NAFLD may be considered an additional feature of the metabolic syndrome, with specific hepatic insulin resistance.
Diabetes 2001 Aug
PMID:Nonalcoholic fatty liver disease: a feature of the metabolic syndrome. 1147 47

Hereditary hemochromatosis (HHC) is an autosomal recessive disorder of iron metabolism characterized by increased iron absorption and deposition in the liver, pancreas, heart, joints, and pituitary gland. Without treatment, death may occur from cirrhosis, primary liver cancer, diabetes, or cardiomyopathy. In 1996, HFE, the gene for HHC, was mapped on the short arm of chromosome 6 (6p21.3). Two of the 37 allelic variants of HFE described to date (C282Y and H63D) are significantly correlated with HHC. Homozygosity for the C282Y mutation was found in 52-100% of previous studies on clinically diagnosed probands. In this review, 5% of HHC probands were found to be compound heterozygotes (C282Y/H63D), and 1.5% were homozygous for the H63D mutation; 3.6% were C282Y heterozygotes, and 5.2% were H63D heterozygotes. In 7% of cases, C282Y and H63D mutations were not present. In the general population, the frequency of the C282Y/C282Y genotype is 0.4%. C282Y heterozygosity ranges from 9.2% in Europeans to nil in Asian, Indian subcontinent, African/Middle Eastern, and Australasian populations. The H63D carrier frequency is 22% in European populations. Accurate data on the penetrance of the different HFE genotypes are not available. Extrapolating from limited clinical observations in screening studies, an estimated 40--70% of persons with the C282Y homozygous genotype will develop clinical evidence of iron overload. A smaller proportion will die from complications of iron overload. To date, population screening for HHC is not recommended because of uncertainties about optimal screening strategies, optimal care for susceptible persons, laboratory standardization, and the potential for stigmatization or discrimination.
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PMID:HFE gene and hereditary hemochromatosis: a HuGE review. Human Genome Epidemiology. 1147 83

The content of body iron is regulated primarily by absorption since humans have no physiological mechanism by which excess iron is excreted. This regulation, however, is not absolute. Many factors such as the content of diets, iron doses, life styles, etc. influence iron absorption. In the past, nutrition programs for iron fortification and the ingestion of iron preparations have been widely practiced because of the seriousness of worldwide iron deficiency. Also, we now know that a significant number of asymptomatic people carry the hemochromatosis gene, HFE, indicating that these people have the potential to accumulate excess body iron in their lifetime. Excess body iron can be highly toxic. This toxicity involves many organs leading to a variety of serious diseases such as liver disease, heart disease, diabetes mellitus, hormonal abnormalities, dysfunctional immune system, etc. The tissue damage associated with iron overload is believed to result primarily from free radical reactions mediated by iron. Iron is an effective catalyst in free radical reactions. The diseases associated with iron overload can be managed effectively or prevented. Therefore, early diagnosis of iron overload and appropriate therapy are critical. By providing the necessary laboratory data, clinical chemistry laboratories can play the pivotal role in the management of these health problems.
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PMID:Chronic iron overload and toxicity: clinical chemistry perspective. 1151 32


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