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)

Hb Evanston [alpha14(A12)Trp --> Arg] is considered to be a rare alpha chain mutant, and was originally observed in two Black families in 1982, inducing a mild Hb H disease phenotype in a homozygous state for the -alpha3.7 deletion ( -alpha(Evanston)/ -alpha). The mutant, evidently linked with one of the two -alpha3.7 thalassemia (thal) alleles, was considered to be unstable and rapidly proteolyzed. We describe Hb Evanston in three new independent Asian cases, all induced by a TGG --> CGG transition. In all cases the mutation is linked to the alpha1-globin gene, either on a wild type allele or in linkage with the common -alpha3.7 and -alpha4.2 deletion alleles. The beta/alpha ratio was balanced in the presence of the mutation only, and accordingly unbalanced in co-inheritance with the deletion defects. Although a second independent mutation event on a -alpha3.7 or a -alpha4.2 deletion allele could not be excluded, we conclude that at least one independent Hb Evanston mutation has occurred on a wild type allele in the Asian populations. Unstable Hb tetramers tend to degrade and disappear during purification. Both Hb Evanston tetramers, formed in combination with normal beta and delta chains, remain perfectly stable after extensive purification and concentration steps, suggesting an early posttranslational thalassemic effect, probably at the dimer/tetramer affinity level.
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PMID:A new Hb evanston allele [alpha14(A12)Trp --> Arg] found solely, and in the presence of common alpha-thalassemia deletions, in three independent Asian cases. 1500 59

A new alpha-globin mutation causing persistent mild hypochromic microcytosis and erythrocytosis is described. Hb Zurich Albisrieden [alpha59(E8)Gly-->Arg (alpha2)] is not detected at the protein level and leads to alpha(+)-thalassemia (thal).
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PMID:A new highly unstable alpha chain variant causing alpha(+)-thalassemia: Hb Zurich Albisrieden [alpha59(E8)Gly-->Arg (alpha2)]. 1565 92

Hemoglobin (Hb) chains have been analyzed traditionally by cellulose acetate electrophoresis after sample extraction with acetone and denaturation with concentrated urea in order to detect thalassemia (Thal). A few capillary electrophoresis (CE) methods have been also described for separation of Hb chains also after sample extraction. We describe a CE method for analysis of Hb chains without sample preparation. Red blood cells were diluted (hemolyzed) in water and injected directly onto the capillary. The separation was performed in concentrated phosphate buffer at pH 12.6 and 2.15. Under these conditions of pH and buffer concentration, the chains were denatured and separated from the heme during electrophoresis. The common variants of the beta-chains, such as beta(S), beta(C), and beta(E), are also separated from each other. The intact Hb molecule is analyzed using the same sample and CE conditions but in an arginine-Tris buffer, pH 8.6. The data from the three separations are used to complement each other for interpretation of the presence of Hb variants and for thalassemia. The main advantages of this method are simplicity and speed. This method illustrates the flexibility and simplicity of the CE for analysis of the hemoglobinopathies.
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PMID:Simplified hemoglobin chain detection by capillary electrophoresis. 1569 Apr 30

We describe, in a Spanish family with moderate microcytosis and hypochromia, a novel nondeletional alpha-thalassemia (thal) mutation localized on the alpha2-globin gene. DNA sequencing revealed a point mutation at codon 125 (CTG --> CGG) in the heterozygous state, that was confirmed by restriction analysis. The resulting variant, which causes a nondeletional alpha-thal, was named Hb Plasencia [alpha125(H8)Leu --> Arg (alpha2)] after the place of residence of the affected family.
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PMID:A novel mutation of the alpha2-globin causing alpha(+)-thalassemia: Hb Plasencia [alpha125(H8)Leu--Arg (alpha2). 1592 Nov 63

We report an unusual north Indian patient with Hemoglobin Evanston [alpha 14 (A12) Try --> Arg] who had acquired cyclic thrombocytopenia (10-1230 x 10(9)/l periodic oscillation of four week duration) which recovered without any specific therapy. She later developed Takayasu's disease and underwent three corrective stents. She is presently in clinical remission and is on regular follow up. To the best of our knowledge our patient is the first report of Hb Evanston from the indigenous population of India and highlights the need to look for point mutations in the alpha globin gene, which may interact with thalassemia or other hemoglobinopathies, in atypical cases. The association of these three disorders in our patient is possibly unrelated though an immune basis for the cyclic thrombocytopenia and Takayasu's disease is likely as seen in this report.
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PMID:Investigation of persistent hypochromic microcytosis unmasks hemoglobin Evanston [alpha 14 (A12) Try--> Arg] in a patient of cyclic thrombocytopenia preceding Takayasu's disease. 1627 37

Accumulating evidence supports the existence of a condition involving hemolysis-associated pulmonary hypertension (PHT). Hemolysis-induced release of cell-free hemoglobin and red blood cell arginase, resulting in impaired nitric oxide bioavailability, endothelial dysfunction, and PHT, has been reported in sickle cell disease. Since thalassemia is also a condition of chronic hemolysis, these patients are at risk. The data demonstrate that hemolysis-induced dysregulation of arginine metabolism and PHT also occurs in thalassemia. Erythrocyte release of arginase during hemolysis contributes to the development of PHT. Therapies that maximize arginine and nitric oxide bioavailability may benefit patients with thalassemia.
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PMID:Hemolysis-associated pulmonary hypertension in thalassemia. 1633 2

The beta-thalassemia (thal) minor phenotypes with normal Hb A2 levels and decreased MCV and MCH values are relatively rare beta-thal traits. Here, we describe a family with normal Hb A2 and decreased MCV and MCH levels. Amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) revealed the IVS-II-1 (G-->A) mutation in the beta-globin gene of the proband and her father. Direct sequencing of the gamma-globin gene of the proband and her father also revealed a previously reported variant called Hb A2-Troodos [gamma116(G18)Arg-->Cys] [in cis with the IVS-II-1 (G-->A) beta0-thal mutation]. This is the first case report of Hb A2-Troodos in association with the beta0 IVS-II-1 mutation. Reduced Hb A2 expression by a concomitant Hb A2 beta-thal in cis or trans, may cause problems in carrier diagnostics, and eventually in genetic counseling and prenatal diagnosis when insufficient molecular analyses are performed.
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PMID:The IVS-II-1 (G-->a) beta0-thalassemia mutation in cis with HbA2-Troodos [delta116(G18)Arg-->Cys (CGC-->TGC)] causes a complex prenatal diagnosis in an Iranian family. 1637 Apr 91

We report a new structural defect of the alpha2-globin chain, not detectable on high performance liquid chromatography (HPLC) or electrophoresis, characterized in a 12-year-old boy of Surinamese-Hindustani origin. The child was suspected to be a carrier of alpha-thalassemia (thal) because of microcytic hypochromic parameters in the absence of iron depletion. Gap-polymerase chain reaction (gap-PCR) revealed only normal fragments in the proband, and the pattern of a -alpha4.2 (leftward) deletion in his father and sister. Direct sequencing of the alpha-globin genes revealed an ACC-->AAC transversion at codon 108 of the alpha2-globin gene in the proband, in his mother and in a younger sister. The new mutation predicts a Thr -->Asn amino acid substitution at the corresponding residue. Threonine, a covalent binder with an R-active OH group, situated in the G helix of the alpha-globin chain, is involved in alpha1beta1 contacts. Asparagine, being an equally covalent binder but with a different R-active H2N-C=O group, could make the mutated chain less suitable for tetramer cooperation. Alternatively, an absent or reduced interaction with the alpha hemoglobin (Hb) stabilizing protein (AHSP) could lead to loss of alpha chains. Hb Bleuland is the first mutation described at codon 108 and is therefore interesting in regard to the possible effects and genetic risk. The nearest variant, Hb Suan-Dok [alpha109(G16)Leu -->Arg, CTG-->CGG (alpha2)] was originally observed in a Thai patient affected with Hb H, in combination with an alpha0-thal allele. The same Hb Suan-Dok mutation, recently described in our laboratory in a carrier of African ancestry, was also not detectable as a protein and presented with an alpha-thal phenotype similar to Hb Bleuland.
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PMID:Hb Bleuland [alpha108(G15)Thr-->Asn, ACC-->AAC (alpha2)]: a new abnormal hemoglobin associated with a mild alpha-thalassemia phenotype. 1684 Feb 25

To help clarify the hematological picture of patients who may be positive for beta- and delta-globin gene mutations, the following study was carried out. Our aim was to identify the delta-globin gene mutations found in the Greek Cypriot population, their frequencies and the Hb A2 values associated with them. Seventy-four samples were selected from a random sample of 5,030 individuals, and the database of the Molecular Genetics Thalassaemia Department containing diagnostic analyses data was also mined for relevant information. Four novel for Cyprus delta-globin gene mutations: -30 (T-->C), Hb A2-Wrens [delta98(FG5)Val-->Met, GTG-->ATG], IVS-I-2 (T-->C) and Hb A2-Yokoshima [delta25(B7)Gly-->Asp (GGT-->GAT)] were identified. Hb A2-Yialousa [delta27(B9)Ala-->Ser, GCC-->TCC], Hb A2-Yokoshima, Hb A2-Troodos [delta116(G18)Arg-->Cys, CGC-->TGC], Hb A2-Pelendri [delta141(H19)Leu-->Pro, CTG-->CCG], codon 4 [delta4(A1)Thr-->Ile], codon 59 (-A), Hb A2-Wrens, IVS-II-897 (A-->G), IVS-I-2, -55 (T-->C) and -30 bring the total to 11 delta-globin alleles found in the Greek Cypriot population. Hb A2-Yialousa is the most common mutation followed by codon 4, with frequencies of 60.7 and 17.8%, respectively.Hb A2 levels above 1.9% have been found to indicate a significantly reduced possibility for the presence of a delta-globin gene mutation in this population. For Hb A2 levels of 1.7 and 1.8% the possibility of a delta-globin gene mutation rises to 90.9% and reaches 100% for lower Hb A2 levels. The frequency of all the mutant delta-globin chromosomes in the sample is 0.0067 and the carrier frequency is 1.26%.
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PMID:Delta-thalassemia in Cyprus. 1698

Congenital erythropoietic porphyria (CEP), an autosomal recessive disorder, is due to mutations of uroporphyrinogen III synthase (UROS). Deficiency of UROS results in excess uroporphyrin I, which causes photosensitization. We evaluated a 3-year-old boy with CEP. A hypochromic, microcytic anemia was present from birth, and platelet counts averaged 70 x 10(9)/L (70,000/microL). Erythrocyte UROS activity was 21% of controls. Red cell morphology and globin chain labeling studies were compatible with beta-thalassemia. Hb electrophoresis revealed 36.3% A, 2.4% A(2), 59.5% F, and 1.8% of an unidentified peak. No UROS or alpha- and beta-globin mutations were found in the child or the parents. The molecular basis of the phenotype proved to be a mutation of GATA1, an X-linked transcription factor common to globin genes and heme biosynthetic enzymes in erythrocytes. A mutation at codon 216 in the child and on one allele of his mother changed arginine to tryptophan (R216W). This is the first report of a human porphyria due to a mutation in a trans-acting factor and the first association of CEP with thalassemia and thrombocytopenia. The Hb F level of 59.5% suggests a role for GATA-1 in globin switching. A bone marrow allograft corrected both the porphyria and the thalassemia.
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PMID:Congenital erythropoietic porphyria due to a mutation in GATA1: the first trans-acting mutation causative for a human porphyria. 1714 89


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