Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hereditary hemochromatosis (HH) is an autosomal recessive disorder of iron metabolism characterized by increased iron absorption and progressive storage resulting in organ damage. HFE gene mutations C282Y and H63D are responsible for the majority of HH cases. A third HFE mutation, S65C, has been associated with the development of a mild form of hemochromatosis. The beta-thalassemia trait is characterized by mild, ineffective erythropoiesis that can induce excess iron absorption and ultimately lead to iron overload. The aim of this study was to evaluate the effect of genetic markers (HFE mutations C282Y, H63D, and S65C) on the iron status of beta-thalassemia carriers. A total of 101 individuals heterozygous for beta-thalassemia and 101 normal control individuals were studied. The allelic frequencies of C282Y (1.5 versus 3.5%), H63D (15.3 versus 18.3%), and S65C (1.0 versus 1.5%) did not differ significantly between beta-thalassemia carriers and normal controls. Serum iron (P=0.029) and transferrin saturation (P=0.009) were increased in beta-thalassemia carriers heterozygous for H63D mutation. The number of subjects carrying C282Y or S65C mutations was too low to conclude their effect on the iron status. These results suggest that the beta-thalassemia trait tends to be aggravated with the coinheritance of H63D mutation, even when present in heterozygosity.
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PMID:The role of HFE mutations on iron metabolism in beta-thalassemia carriers. 1553 48

beta-Thalassaemia major is an inherited blood disorder which is complicated by repeated blood transfusion and excessive gastrointestinal iron (Fe) absorption, which leads to toxic Fe overload. Current treatment using the chelator, desferrioxamine (DFO), is expensive and cumbersome since the drug requires long subcutaneous infusions and it is not orally active. A novel chelator, 2-pyridylcarboxaldehyde 2-thiophenecarboxyl hydrazone (PCTH), was recently designed and shown to have high Fe chelation efficacy in vitro. The aim of this investigation was to examine the Fe chelation efficacy of PCTH in vitro implementing primary cultures of cardiomyocytes and in vivo using mice. We showed that PCTH was significantly (P<0.005) more effective than DFO at mobilising (59)Fe from prelabelled cardiomyocytes. Moreover, PCTH prevented the incorporation of (59)Fe into ferritin during Fe uptake from (59)Fe-labelled transferrin. These effects were important to assess as cardiac complications caused by Fe deposition are a major cause of death in beta-thalassaemia major patients. Further studies showed that PCTH was orally active and well tolerated by mice at doses ranging from 50 to 200 mg/kg, twice daily (bd), for 2 days. A dose-dependent increase in faecal (59)Fe excretion was observed in the PCTH-treated group. This level of Fe excretion at 200 mg/kg was similar to the same dose of the orally effective chelators, pyridoxal isonicotinoyl hydrazone (PIH) and deferiprone (L1). Effective Fe chelation in the liver by PCTH was shown via its ability to reduce ferritin-(59)Fe accumulation. Mice treated for 3 weeks with PCTH at doses of 50 and 100 mg/kg/bd showed no overt signs of toxicity as determined by weight loss and a range of biochemical and haematological indices. In subchronic Fe excretion studies over 3 weeks, PIH and PCTH at 75 mg/kg/bd for 5 days/week increased faecal (59)Fe excretion to 140% and 145% of the vehicle control, respectively. This study showed that PCTH was well tolerated at 100 mg/kg/bd and induced considerable Fe excretion by the oral route, suggesting its potential as a candidate to replace DFO.
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PMID:PCTH: a novel orally active chelator of the aroylhydrazone class that induces iron excretion from mice. 1560 19

In the majority of cases, microcytosis is the result of impaired hemoglobin synthesis. Disorders of iron metabolism and protoporphyrin and heme synthesis, as well as impaired globin synthesis, lead to defective hemoglobin production and to the generation of microcytosis and microcytic anemia. Iron deficiency anemie, anemia of chronic diseases, thalassemias, congenital sideroblastic anemias and homozygous HbE disease are the main representatives of microcytosis and microcytic anemias. Serum iron, total iron binding capacity, transferrin saturation, serum ferritin, serum transferrin receptor, transferrin receptor-ferritin index, and zinc-protoporhyrin concentration in erythrocytes are tests used for assessment of iron deficiency. The convention laboratory test for diagnosing iron deficiency is the measurement of serum ferritin. The most precise method for evaluating body iron stores is the examination for iron on aspirated bone marrow or marrow biopsy. Increased content of Hb A2 over 3.5% is diagnostic for beta-thalassemia. Presence of ringed sideroblasts is characteristic of sideroblastic anemias. Hemoglobin electrophoresis is required for the diagnosis of hemoglobinopathy E. The optimal therapeutic regimen in iron deficiency anemia used in this country is to administer 100 mg of elemental iron twice daily separately from meals. Ferrous sulphate (Ferronat Retard tbl. or Sorbifer Dulures tbl.) which are slow-releasing iron formulations are preferred because of their low cost, high bioavailability and low side-effects. Parenteral iron therapy is justified only in patients who cannot absorb iron, who have blood losses that exceed the maximal absorptive capacity of their intestinal tract or who are totally intolerant of oral iron. However, parenteral iron therapy may be associated with serious and even fatal side-effects.
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PMID:[Microcytic and hypochromic anemias]. 1563 79

Labile plasma iron (LPI) represents a component of non-transferrin-bound iron (NTBI) that is both redox-active and chelatable, capable of permeating into organs and inducing tissue iron overload. It appears in various types of hemosiderosis (transfusional and non-transfusional) and in other iron-overload conditions. Sustained levels of LPI could over time compromise organ (e.g. heart) function and patient survival. With the advent of methods for measuring LPI in the clinical setting, it has become possible to assess the implications of LPI in the management of iron overload based on regimens of iron chelation. As LPI is detected primarily in patients with transfusional iron overload and other forms of hemosiderosis, we review here regimens of iron chelation with deferrioxamine and deferiprone (separately or combined) in terms of their efficacy in minimizing daily exposure to LPI in thalassemia major and thalassemia intermedia patients.
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PMID:LPI-labile plasma iron in iron overload. 1573 90

The average results of some laboratory measurements, including the hemoglobin, mean corpuscular volume (MCV), serum transferrin saturation (TS), serum ferritin, and white blood cell count of African-Americans differ from those of whites. Anonymized samples and laboratory data from 1491 African-American and 31 005 white subjects, approximately equally divided between men and women, were analyzed. The hematocrit, hemoglobin, MCV, TS, and white blood cell counts of African-Americans were lower than those of whites; serum ferritin levels were higher. When iron-deficient patients were eliminated from consideration the differences in hematocrit, hemoglobin, and MCV among women were slightly less. The -3.7-kilobase alpha-thalassemia deletion accounted for about one third of the difference in the hemoglobin levels of African-Americans and whites and neither sickle trait nor elevated creatinine levels had an effect. Among all subjects, 19.8% of African-American women would have been classified as "anemic" compared with 5.3% of whites. Among men, the figures were 17.7% and 7.6%. Without iron-deficient or thalassemic subjects, the difference had narrowed to 6.1% and 2.77% and to 4.29% and 3.6%, respectively. Physicians need to take into account that the same reference standards for hemoglobin, hematocrit, MCV, and TS and the white blood cell count do not apply to all ethnic groups.
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PMID:Hematologic differences between African-Americans and whites: the roles of iron deficiency and alpha-thalassemia on hemoglobin levels and mean corpuscular volume. 1649 11

At age of 3.2 years routine blood analysis showed the presence of a beta-thalassemic trait with unexpected high level of serum iron and high transferrin saturation. Hematological follow-up confirmed the moderate degree of anemia and persisting high levels of iron indices throughout the years with a progressive increase of serum ferritin. At the age of 19 years the patient was diagnosed homozygous for HC63D HFE. The patient referred by us confirm the possibility of precocious alteration of iron indices in patients with heterozygosity for beta-thalassemia inherited together with HFE mutations. This observation suggests that any children with thalassemic trait with increased transferrin saturation and/or serum ferritin might be investigated for the presence of the hemocromatosis genes in order to detect the disease before any clinical manifestation and even before organ iron loading.
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PMID:Heterozygous beta-thalassemia and homozygous H63D hemochromatosis in a child: an 18-year follow-up. 1580 2

Chronic red blood cell transfusion support in patients with myelodysplastic syndromes (MDS) is often necessary but may cause hemosiderosis and its consequences. The pathophysiologic effects of iron overload relate to increased non-transferrin bound iron generating toxic oxygen free radicals. Studies in patients with MDS and thalassemia major have shown adverse clinical effects of chronic iron overload on cardiac function in patients who underwent polytransfusion. Iron chelation therapy in patients with thalassemia who were effectively chelated has prevented or partially reversed some of these consequences. A small group of patients with MDS who had undergone effective subcutaneous desferrioxamine (DFO) chelation for 1 to 4 years showed substantial hematologic improvements, including transfusion independence. However, because chronic lengthy subcutaneous infusions of DFO in elderly patients have logistic difficulties, this chelation therapy is generally instituted late in the clinical course. Two oral iron chelators, deferiprone (L1) and deferasirox (ICL670), provide potentially useful treatment for iron overload. This article reviews data indicating that both agents are relatively well tolerated, were at least as effective as DFO for decreasing iron burdens in comparative thalassemia trials, and (for deferiprone) were associated with improved cardiac outcomes. These outcomes could potentially alter the tissue siderosis-associated morbidity of patients with MDS, particularly those with pre-existing cardiac disease.
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PMID:Myelodysplastic syndromes: iron overload consequences and current chelating therapies. 1640 8

Our laboratories have prepared a novel class of iron (Fe) chelators of the 2-pyridylcarboxaldehyde isonicotinoyl hydrazone (PCIH) class. This article will review the iron chelation efficacy of this series of chelators, both in cell culture and in animal models. Several PCIH analogs were shown to be effective at inducing iron mobilization and preventing iron uptake from the iron-transport protein, transferrin. Moreover, several of these ligands were effective at permeating the mitochondrion and inducing iron release. Studies in mice demonstrated that the PCIH analog, PCTH, was orally active and well tolerated by mice at doses ranging from 50 to 100 mg kg(-1), twice daily (b.d.). A dose-dependent increase in fecal 59Fe excretion was observed in the PCTH-treated group. This level of iron excretion was similar to that found for the orally effective chelators, pyridoxal isonicotinoyl hydrazone (PIH) and deferiprone (L1). The PCIH group of ligands clearly has the potential for the treatment of beta-thalassemia (thal) and Friedreich's Ataxia (FA).
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PMID:PCTH: a novel orally active chelator for the treatment of iron overload disease. 1654 Apr 21

Some variant proteins cause diseases, and some diseases result in increases of proteins with abnormally modified structures. The detection, characterization, and estimation of the relative amounts of protein variants and abnormally modified proteins are important for clinical diagnosis and for elucidation of the mechanisms of the pathogenesis of diseases. Analysis of the covalent structures of proteins using matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) and liquid chromatography-electrospray ionization MS (LC-ESI-MS), which had been developed by the early 1990s, have largely replaced analyses by conventional protein chemistry. Here, we review the detection and characterization of hemoglobin variants, HbA1c measurement, detection of carbohydrate-deficient transferrin, and identification of variants of transthyretin (TTR) and Cu/Zn-superoxide dismutase (SOD-1) using soft ionization MS. We also propose the diagnostic application of the signals of modified forms of TTR, that is, S-sulfonated TTR and S-homocysteinyl TTR. The relative peak height ratio of the abnormal/normal components gives valuable information about the instability of variants and enables the detection of unstable Hb subunits or thalassemia heterozygotes. We found unique modified structures of TTR that suggested changes in amyloid fibrils.
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PMID:Detection and characterization of variant and modified structures of proteins in blood and tissues by mass spectrometry. 1656 75

Microcytic erythropoiesis in case of anemia is frequently due to iron deficiency or may be due to alpha- and beta- thalassemia trait as a result of increased activity of erythropoiesis. The aim of the present study was to evaluate alterations with regard to the degree of hemoglobinization in reticulocytes in comparison with mature erythrocytes. Iron availability in subjects with anemia resulting from iron deficiency and alpha- or beta- thalassemia was studied by application of conventional as well hemocytometric parameters that have recently become available. Participants of the study were reference subjects (n=75), subjects with iron deficiency anemia (IDA, n=52) and alpha- (n=26) or beta-thalassemia trait (n=24). If compared with the reference group obviously increased RBC counts together with decreased values for RDW-sd and MCHC were established in case of alpha- and beta- thalassemia subjects. Deviations were demonstrated to be more pronounced in case of beta- thalassemia. Accelerated erythropoiesis in the case of subjects with IDA and beta-thalassemia is manifested by detection of increased results for immature reticulocyte counts. In particular in case of beta- thalassemia, elevated reticulocyte counts combined with slightly increased values for ZPP/heme ratio reflect increased activity of erythropoiesis. In the case of subjects with beta-thalassemia serum transferrin concentrations revealed slightly decreased results, whereas serum ferritin and iron concentrations demonstrated a tendency towards higher values if compared with the group of reference subjects. At a definitive MCV level, the hemoglobin content of reticulocytes is decreased in the case of IDA if compared with the alpha- or beta- thalassemia trait. For the ratio of hemoglobin content of reticulocytes and erythrocytes, obviously decreased results are demonstrated in the case of subjects with iron deficiency anemia (1.02 +/- 0.08, mean +/- SD) and in the case of beta-thalassemia (1.06 +/- 0.04) if compared with the group of reference subjects (1.11 +/- 0.02) and a-thalassemia (1.11 +/- 0.07). Evaluation of the hemoglobinization state should be performed by means of pattern recognition in concordance with characteristic profiles for parameters reflecting the actual iron state. In case of therapy the result of intervention can be appropriately monitored by longitudinal follow-up.
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PMID:Hemoglobinization and functional availability of iron for erythropoiesis in case of thalassemia and iron deficiency anemia. 1658 56


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