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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

25-yr old female identical twins of Italian-American origin concordant for sickle beta-thalassemia were studied to explain their clinical differences. One of them has been severely affected from childhood with one aplastic crisis, an earlier onset of vaso-occlusive crises, and recent cardiac decompensation; the other twin shows no cardiac decompensation. Similar are their degree of anemia, RBC indices, blood volumes, absence of splenic sequestration, depression of pO2, elevation of p50 and 2,3-DPG, hemoglobin composition, and peripheral blood globin-synthetic rates. Regarding differences, the more severely affected has a shorter 51Cr RBC life span, a greater menstrual blood loss, and is more overweight, whereas the less severely affected has functional asplenia by 99mTc scanning and a larger proportion of RBC with decreased cellular deformability. We conclude that in sickle beta-thalassemia: (1) genotype alone does not determine the clinical course; (2) significant differences in clinical course can occur with almost identical hemoglobin composition and globin synthetic rates; (3) cellular deformability changes do not correlate exactly with clinical course; and (4) functional asplenia and leanness may be advantageous.
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PMID:Sickle beta-thalassemia: identical twins differing in severity implicate nongenetic factors influencing course. 98 45

Further studies have been carried out on blood of the 15-year-old Negro male from Baltimore who was the first reported case of the homozygous state for hereditary persistence of fetal haemoglobin. His red cells contain only Hb F; Hbs A and A2 have never been detected. Over a 15-year period of follow up the red cells of this individual have shown persistent microcytosis with reduced MCH and MCV values. His whole-blood p50 value is decreased, probably because of lack of interaction between Hb F and 2,3-diphosphoglycerate. However, his haemoglobin level at the age of 15 years is lower than would be predicted from the degree of increased oxygen affinity. Globin-chain synthesis studies suggest that this is because he has a mild thalassaemia disorder with an alpha/gamma-chain production ratio of about 1.5, similar to that found in beta-thalassemia heterozygotes. Thus Negro HPFH appears to be a well-compensated form of delta beta thalassaemia.
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PMID:The Negro variety of hereditary persistence of fetal haemoglobin is a mild form of thalassaemia. 99 Jan 87

The interaction of rare Hb variants with beta(0)-thalassaemia results in a quasihomozygous state where the erythrocytes contain the variant as the only major adult Hb component. Such a situation is a unique model that enables functional studies even in the case of a neutral variant that could not be isolated from Hb A. We report here an unusual patient carrying Hb Arta, a novel Hb variant [beta 45 (CD4) Phe-->Cys], in trans with beta(0)-thalassaemia gene (beta(0) 39). The aminoacid substitution at the critical CD corner of this Hb molecular renders the molecule unstable. In addition, haem is displaced in a position that favours the deoxy (T) conformation of the variant, but less than in Hb Cheverly [beta 45 (CD4) Phe-->Ser], and results in a p50 of 43 mmHg (pH 7.4, 37 degrees C) in the red cells with preservation of cooperativity. Solution studies of the almost pure Hb Arta show a 50% decrease in oxygen affinity and normal cooperativity; the Bohr effect and the interaction with organic phosphates are similar to those of Hb A. Hb Arta retains both normal homo- and heterotropic effects allowing a well-preserved oxygen transport in vivo despite a mild anaemia.
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PMID:Hb Arta [beta 45 (CD4) Phe-->Cys]: a new unstable haemoglobin with reduced oxygen affinity in trans with beta-thalassaemia. 855 60

Abnormalities of hemoglobin (Hb) synthesis are among the most common inherited disorders of man and can be quantitative (thalassemia syndromes) or qualitative (variant Hbs). Definite identification of hemoglobinopathies can be achieved by a stepwise algorithmic approach, starting with a detailed clinical history, through hematologic evaluation [complete blood count (CBC)], reticulocyte count, red blood cell (RBC) morphology], protein based analytic methods [Hb electrophoresis or isoelectric focusing (IEF), cation exchange high performance liquid chromatography (HPLC), reversed phase HPLC] to nucleic acid based methods [such as polymerase chain reaction (PCR), reverse transcribed (RT)-PCR, sequencing of genomic DNA and sequencing of RT-PCR amplified globin cDNA of the gene of interest]. When an abnormality of Hb function (increased or decreased oxygen affinity) or stability (unstable Hb variants) is suspected from the phenotype, special confirmatory tests (determination of p50, Heinz body prep and isopropanol or heat stability tests) can be useful. Family studies are also helpful in certain cases. A review of the application of these methods to the diagnosis of hemoglobinopathies at the Sickle Cell Center Laboratory in Augusta, GA, USA, is presented below.
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PMID:Diagnostic approach to hemoglobinopathies. 1748 7