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

The molecular basis of most beta-thalassemia syndromes has been defined, while the spectrum of mutations causing delta-thalassemia is not well characterized. In an attempt to identify such mutations, the region encompassing the delta-globin gene from three Greek Cypriot families suspected of having delta-thalassemia was amplified by polymerase chain reaction (PCR), and DNA sequence determined using an automated fluorescence-based sequencer. Four novel mutations were identified: a G----T change at codon 27 that results in an alanine to serine change; a C----T change at codon 116 converting arginine to cysteine; a T----C change at codon 141 converting leucine to proline; and an AG----GG change at the consensus 3'-acceptor site in IVS-2. While the latter is clearly a thalassemic mutation, the low hemoglobin A2 in the first three may be due to either decreased production or instability of the altered delta-globin chain. All four mutations may be detected by PCR amplification of genomic DNA followed by restriction enzyme digestion. Two mutations abolish restriction sites while two create new cleavage sites. Screening for molecular defects that cause delta-thalassemia or unstable delta-globin by PCR amplification and restriction enzyme digestion will lead to correct diagnosis of beta/delta-thalassemia compound heterozygotes and improved genetic counseling.
Blood 1991 Dec 15
PMID:Identification of four novel delta-globin gene mutations in Greek Cypriots using polymerase chain reaction and automated fluorescence-based DNA sequence analysis. 174 90

The aim of this study was to determine the crude prevalence of alpha-thalassemia traits in Taiwan. A total of 1435 healthy employees from a statewide company were randomly screened by complete blood count determination with indices. Subjects with mean corpuscular volume less than 80 fl were analyzed by hemoglobin electrophoresis on cellulose acetate to exclude beta-thalassemia and with serum ferritin to exclude iron deficiency. Modified hemoglobin H inclusion staining was performed to confirm the diagnosis of alpha-thalassemia traits, and DNA probe studies were used to confirm the validity of this test. The overall prevalence rate of alpha-thalassemia trait was 3.4% (48 out of 1435). In persons of mainland Chinese origin, prevalence was 0.4%, and among persons of Taiwanese origin, it was 4.0% (47 out of 1171). We conclude that alpha-thalassemia traits are common genetic disorders in Taiwan and that antenatal screening is advised to reduce the frequency of occurrence of hemoglobin Bart's hydrops fetalis. The methods we used proved to be reliable and inexpensive.
J Lab Clin Med 1991 Dec
PMID:Alpha-thalassemic traits are common in the Taiwanese population: usefulness of a modified hemoglobin H preparation for prevalence studies. 174 8

A defect in urine concentrating ability occurs in individuals with sickle cell trait (HbAS). This may result from intracellular polymerization of sickle hemoglobin (HbS) in erythrocytes, leading to microvascular occlusion, in the vasa recta of the renal medulla. To test the hypothesis that the severity of the concentrating defect is related to the percentage of sickle hemoglobin present in erythrocytes, urinary concentrating ability was examined after overnight water deprivation, and intranasal desmopressin acetate (dDAVP) in 27 individuals with HbAS. The HbAS individuals were separated into those who had a normal alpha-globin genotype (alpha alpha/alpha alpha), and those who were either heterozygous (-alpha/alpha alpha) or homozygous (-alpha/-alpha) for gene-deletion alpha-thalassemia, because alpha-thalassemia modulates the HbS concentration in HbAS. The urinary concentrating ability was less in the alpha alpha/alpha alpha genotype than in the -alpha/alpha alpha or -alpha/-alpha genotypes (P less than 0.05). After dDAVP, the urine osmolality was greater in patients with the -alpha/-alpha genotype than with the -alpha/alpha alpha genotype (882 +/- 37 vs. 672 +/- 38 mOsm/kg H2O) (P less than 0.05); patients with the -alpha/alpha alpha genotype had greater concentrating ability than individuals with a normal alpha-globin gene arrangement. There was an inverse linear correlation between urinary osmolality after dDAVP and the percentage HbS in all patients studied (r = -0.654; P less than 0.05). A linear correlation also existed for urine concentrating ability and the calculated polymerization tendencies for an oxygen saturation of 0.4 and O (r = -0.62 and 0.69, respectively). We conclude that the severity of hyposthenuria in HbAS is heterogeneous. It is determined by the amount of HbS polymer, that in turn is dependent upon the percentage HbS, which is itself related to the alpha-globin genotype.
J Clin Invest 1991 Dec
PMID:Effects of alpha-thalassemia and sickle polymerization tendency on the urine-concentrating defect of individuals with sickle cell trait. 175 55

Five beta-thalassaemia mutations hitherto undescribed in Asian Indians were identified in beta-thalassaemia carriers originating from the Indian subcontinent by direct sequencing of their beta-globin genes which were amplified by the polymerase chain reaction (PCR). A T-G substitution at IVS 2 position 837, which probably creates an alternative acceptor splice site and a T insertion in codon 88, resulting in a shift in the reading frame with a premature stop codon, are new beta-thalassaemia mutations. The others were framshift codon 5 (-CT), IVS 1 position 110 (G-A) and IVS-1 minus 1 (G-A) which have been described previously in other populations. These results complete the characterization of the beta-thalassaemia mutations in 708 carriers of Asian Indian origin and will enable a comprehensive programme of carrier screening and prenatal diagnosis of beta-thalassaemia in this population.
Br J Haematol 1991 Dec
PMID:Rare beta-thalassaemia mutations in Asian indians. 177 86

An etiological examination was performed on the DNA of a 13-year-old Zairean girl, who had some abnormalities in hematological and red cell morphological examinations and was homozygote for an abnormal Hb like HbS. DNA was amplified by the PCR method to obtain 1.7 kb size DNA containing the 5' region of the beta globin gene. The amplified DNA was digested with Eco 81 I and electrophoresis of the digest revealed the absence of its active site, which is on codons beta 5-7 (CCTGAGGAG) of the normal DNA. Sequencing of the cloned DNA by the dideoxy method confirmed that the codon beta 6 (GAG, Glu) mutated to a new codon GTG (Val) which is the beta S globin gene producing abnormal HbS. The haplotype of the chromosome having beta S gene was --+---++, which is the most common type in Zaire area. On the other hand, when the genomic DNA was digested with Bgl II or Bam HI and hybridized to an alpha probe, a fragment (16 kb/Bgl II or 10.5 kb/Bam HI) in addition to the normal ones (12.5 and 7.5 kb/Bgl II or 14 kb/Bam HI) was observed. This resulted from the deletion of 3.7 kb from the alpha gene arrangement, which led to alpha-thalassemia-2 (genotype: alpha 3.7-/alpha alpha). A family study demonstrated that her parents were heterozygote for HbS and her father had alpha-thalassemia-2.
Rinsho Byori 1991 Dec
PMID:[Molecular analysis of an African family with sickle cell disease and alpha-thalassemia-2]. 177 70

We assessed the iron load content in 36 beta-thalassemia patients by NMR correlating the results with serum ferritin levels. 22 of them were affected by beta-thalassemia major on hyper-transfusional regimen (Group A), 4 by beta-thalassemia intermedia (Group B) and 10 by beta-thalassemia major, who had been previously bone marrow transplanted (Group C). In A and C Groups the liver showed the lowest signal intensity on spin echo images (p less than 0.01; p less than 0.06, respectively). A significant correlation between the summation of signals obtained from all the examined organs and serum ferritin levels was observed by evaluating both all the patients globally (r = 0.78; p less than 0.001) and the A and C Group patients. This correlation was confirmed only in the liver both in all the patients (r = 0.77; p less than 0.001) and in A and C Group patients, when the signals obtained from each organ were evaluated.
Minerva Pediatr 1991 Dec
PMID:[Nuclear magnetic resonance and iron overload in thalassemia]. 179 2

Over the past 20 years allogeneic bone marrow transplantation has been increasingly utilized in the treatment of acute and chronic leukemias, aplastic anemia, severe forms of thalassemia, immunodeficiency syndromes and metabolic disorders due to a lack of specific enzymes in the monocyte-macrophage system. Despite the overall success of this approach and besides the so-called classic complications arising from the toxicity of the conditioning regimen, occurrence of GVH disease and interstitial pneumonitis, there are other less common complications which have been reported mainly by teams transplanting on a large number of patients. With only a limited experience, concerning 60 patients with transplants between May 1987 and May 1991, we have seen some unusual complications such as toxoplasma encephalitis, myasthenia gravis and aseptic bone necrosis, which may give rise to difficult diagnostic and therapeutic decisions.
Acta Med Port 1991 Dec
PMID:[Unusual complications of bone marrow transplantation. Experience at the BMT Unit of the Francisco Gentil Portuguese Institute of Oncology, Lisbon Center]. 180 30

A screening programme involving 9,822 hospitalised patients revealed the frequency of individuals with S gene to be 11.1 per cent. A population survey of 1,000 randomised subjects from amongst about 70,000 people in one block of the area showed the frequency to be 15.1%. The gene is not confined to tribal peoples, but is prevalent throughout the society, being more frequent in scheduled castes and some caste Hindus. With the available Indian data a sickle cell belt can be mapped out in the country. Analysis of clinical data on the first 700 cases of sickle cell disease seen in the Sickle Cell Research Centre (ICMR) at Burla shows patients of all ages, even beyond 40 years, though many patients tend to die by 20 years of age. Genetically, while most patients are SS and 8.1% are S-beta thalassaemia, cases of SD disease and SE disease were also encountered. A frequency of 0.32% of alpha thalassaemia gene was noted in SS patients against 0.28% in sickle cell trait and 0.12% in AA controls. The disease was found to manifest as early as 3 months or may remain asymptomatic till adult life. Though generally running a milder course, moderate to severe anaemia, vaso-occlusive attacks (86.5-89.36%), splenic sequestration (8.43%-12.76%), crippling avascular bone necrosis (5.7%-35.08%), osteomyelitis (5/700), and epistaxis (28.92%-35.08%) remain a few clinical events deserving competent and urgent medical management.(ABSTRACT TRUNCATED AT 250 WORDS)
J Assoc Physicians India 1991 Dec
PMID:Sickle cell disease in India. 830 34

Two cases of spinal cord compression due to extramedullary haemopoiesis in haemoglobine E thalassaemia are described. Possible mechanisms and treatment modes are discussed.
J Assoc Physicians India 1991 Dec
PMID:Spinal cord compression in HbE-thalassaemia. 181 27

A novel beta-chain, beta 126(H4)Val----Gly, electrophoretically silent, was detected by reverse-phase high performance liquid chromatography in three unrelated families from Naples (Southern Italy) and accounted for about 30% of the total beta-chains. The amino acid substitution was detected by HPLC fingerprint. The eight heterozygous patients showed hematologic and biosynthetic alterations of mild beta-thalassemia type. The hemoglobin variant showed abnormal stability features. It was unstable in the heat stability and isopropanol precipitation tests, but did not cause a hemolytic syndrome in vivo and was stable in a time-course experiment of biosynthesis in vitro. DNA polymerase chain reaction direct sequencing of the mutated gene from 135 nt upstream of the cap site to 106 nt downstream of the polyadenylation site showed only the beta 126 GTG----GGG mutation, which was confirmed in the other patients by allele-specific oligonucleotide hybridization. The mutation was found to be associated with a type II beta-globin framework and restriction fragment length polymorphism haplotype V. The novel variant was named hemoglobin Neapolis.
Blood 1991 Dec 01
PMID:Hemoglobin Neapolis, beta 126(H4)Val----Gly: a novel beta-chain variant associated with a mild beta-thalassemia phenotype and displaying anomalous stability features. 195 92


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