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

We determined the complete nucleotide sequence of the 5' noncoding region and the first 74 amino acids of the nonfunctional beta-globin mRNA in a patient with homozygous beta 0 thalassemia. We identified the molecular defect as a single nucleotide substitution in the coding region of the mRNA. At the position corresponding to amino acid 17, replacement of an adenine by a uracil changes the triplet AAG, which codes for lysine in the normal beta chain, to an amber termination codon, UAG. This type of beta 0 thalassemia represents an example of a nonsense mutation in man.
 ...
PMID:beta 0 thalassemia, a nonsense mutation in man. 8 35

The common form of beta thalassaemia associated with elevated haemoglobin A2 levels can be broadly classified as beta + or beta 0 type according to the presence or absence of beta-globin chain synthesis in the homozygous state. The molecular pathology of each type is heterogeneous. Apart from a subgroup of Indo-Pakistani patients, the beta-globin structural gene is intact in the majority of patients with beta 0 thalassaemia. The amount of beta-globin mRNA present in the reticulocytes of these patients varies: in some it is absent or barely detectable; in others, a substantial amount is present, but it is nonfunctional. We recently demonstrated that the molecular lesion in a Chinese patient with nonfunctional beta-globin mRNA was due to the mutation of the normal lysine codon AAG at amino acid 17 to the amber terminator codon UAG, which prematurely terminates the beta-globin chain. In the present study we demonstrate the first example of a nonsense mutation in humans which can be suppressed in vitro by the suppressor tRNA, as has been found in other eukaryotic cells and viruses.
 ...
PMID:Suppression of the nonsense mutation in homozygous beta 0 thalassaemia. 49 26

beta-Globin genes in 294 chromosomes of beta-thalassemia homozygotes and patients of beta-thalassemia/HbE in the northeast, the middle and the south of Thailand were analyzed by the PCR related techniques: dot blot hybridization, direct restriction assay, direct cloning and direct sequencing of the amplified DNA fragments. Twelve different mutations were detected at various frequencies. They are an A-G at-28, codon 19 (AAC-AGC), a G-T at IVS-1 nt1,a G-C at IVS-1 nt5, a C-T at IVS-2 nt654, a G addition in codons 8/9, a C deletion in codon 41, a 4 bp deletion in codons 41/42, an A addition in codons 71/72, an AAG-TAG in codon 17, a CAG-TAG in codon 26, a TAC-TAA in codon 35 and a 8 bp deletion in codons 123-125. We also developed allele specific-polymerase chain reaction to facilitate non-radioactive detection of the mutation. Origins and spread of mutations are speculated based on the results of determination of haplotypes and frameworks that are linked to the thalassemia alleles.
 ...
PMID:Molecular heterogeneity of beta-thalassemia in Thailand. 136 6

To enable the prenatal diagnosis of beta-thalassemia by direct detection of the mutant beta-globin genes, we have determined the spectrum of mutations causing this disease in Thailand. The techniques employed included a combination of synthetic oligonucleotide probe hybridization, direct sequencing of genomic DNA enzymatically amplified by the polymerase chain reaction, and cloning and sequencing of the beta-globin genes. A total of 116 beta-thalassemia genes from 78 Hb E/beta-thalassemia patients and from 19 homozygous beta-thalassemia patients were analyzed, and the mutation was characterized in 112/116 (97%) of them. Eleven mutations were found, of which four (-CTTT in codon 41/42, AAG----TAG in codon 17, C----T in position 654 of the IVS-2 region, and A----G in position -28 upstream of the beta-globin gene) accounted for 83%; two previously undescribed mutations have been identified. The spectrum of beta-thalassemia mutations is similar to that reported among the Chinese. However, within the Thai population itself, patients with homozygous beta-thalassemia show a wider spread of mutations in comparison with the Hb E/beta-thalassemia group, in whom the frameshift 41/42 mutation predominates at a frequency of 62%. This difference in distribution may reflect the difference in ethnic origin of the two groups. Characterization of these mutations should aid the planning of a prenatal diagnosis program for beta-thalassemia in Thailand.
 ...
PMID:The molecular basis of beta-thalassemia in Thailand: application to prenatal diagnosis. 239 18

The presence of various substitutions and deletions resulting in beta-thalassemia was studied in 19 black patients with homozygous beta-thalassemia and in numerous relatives; all patients were from Georgia, South Carolina, and Alabama. Methodology included gene mapping, amplification of genomic DNA with Taq polymerase, identification of known nucleotide substitutions or a single nucleotide deletion through hybridization with synthetic oligonucleotides, cloning and sequencing of a beta-globin gene, and sequencing of amplified genomic DNA. Of the 38 chromosomes tested, 21 (55%) had the A----G substitution at nt -29, eight (21%) had the C----T substitution at nt -88, three (8%) had the substitution at codon 24, while one each of the following abnormalities were also detected: frameshift at codon 6, a C----A mutation at nt 848 of the beta IVS-II (new), an A----T mutation at codon 61 (new), a deletion of 1.35 kilobases including the 5' end of beta, a Ggamma(Agamma delta beta)(0)-thalassemia, and one thalassemia determinant that remained unidentified. The C----A mutation at nt 848 of IVS-II occurred at a position 3 nucleotides 5' to the third exon, adjacent to the invariant AG dinucleotide of the acceptor sequence. The A----T mutation in codon 61 (AAG----TAG) resulted in the creation of a stop codon and thus in beta(0)-thalassemia. The various mutations occurred on chromosomes with different haplotypes; however, chromosomes with a specific mutation but with different haplotypes belonged to one specific framework, which suggested that crossovers were responsible for these different types. Hemoglobin (Hb) F levels were generally high (55% to 75% with 98.5% in one patient with beta(0)/beta(0)); a few patients with specific haplotypes and an alpha-thalassemia-2 heterozygosity had a lower Hb F level. The Ggamma in the Hb F was consistently high when the C----T mutation occurred at nt -158 to the Cap site of the Ggamma-globin gene; seven patients with +/+ at this site had an average Ggamma of 73.8%, eight patients with +/- had 64.8%, and one patient with -/- had 34.2%. Variations in hematologic values and in Hb F, Ggamma, and Hb A2 levels of relatives with a beta-thalassemia heterozygosity depended to some extent on the types of mutations or deletions and on the haplotypes of the chromosomes with the beta-thalassemia determinant.
 ...
PMID:Clinical and genetic heterogeneity in black patients with homozygous beta-thalassemia from the southeastern United States. 245 45

Enzymatic DNA amplification and polyacrylamide gel electrophoresis, which demonstrate different sizes of DNA fragments, were used to detect the common mutations causing beta-thalassemia and hemoglobin (Hb) E in Thai people. The 4-bp deletion at codons 41 and 42 can be detected directly by polyacrylamide gel electrophoresis and ethidium bromide staining. Whereas the nonsense mutations at codon 17 (AAG----TAG) and Hb E (GAG----AAG at codon 26) were detected after digestion of the amplified DNA with the enzymes MaeI and MnlI, respectively.
 ...
PMID:Detection of beta-thalassemia and hemoglobin E genes in Thai by a DNA amplification technique. 254 10

A total of 72 chromosomes from 36 Indonesian patients, 23 with beta-thalassemia major and 13 with Hb E-beta-thalassemia, were analyzed by specific oligonucleotide hybridization after DNA amplification. Thirteen had the beta E mutation (codon 26 GAG----AAG). Of the 59-beta-thalassemic chromosomes, 32 were of the variant IVS-1 nt5 (G----C). Seven had the mutation IVS-2 nt654 (C----T), one had the mutation codon 41/42 (deletion CTTT), and one had the mutation codon 17 (AAG----TAG). Another six with the mutation IVS-1 nt1 (G----T), one with the mutation IVS-1 nt1 (G----A), four with the mutation codon 15 (TGG----TAG), one with a mutation codon 30 (AGG----ACG), and one with a mutation codon 35 (deletion C) were first identified by direct sequencing of a patient's genomic DNA followed by further hybridizing other patients' DNA with the appropriate oligonucleotide probes. Five did not carry the common mutations previously described in Asian populations. The four most prevalent mutations encountered made up 83% of the total number of beta-thalassemic chromosomes studied. The most common mutation, IVS-1 nt5 (G----C), was mostly associated with two different haplotypes.
 ...
PMID:Beta-thalassemia mutations in Indonesia and their linkage to beta haplotypes. 258 24

Characterization of beta-thalassemia mutations were attempted for 29 Japanese families clinically diagnosed as having beta-thalassemia. Following the identification of a mutation by cloning and sequencing, all families were screened for this particular mutation, using biotinylated allele-specific oligonucleotide probes. Seven different mutations were detected in 17 families: Six families had the frameshift mutation at codons 41/42, resulting from a 4 nucleotide deletion (TTCTTT----TT); four had the deletion at codons 127/128 (CAGGCT----CCT); and three had the TATA box mutation at nucleotide -31 (A----G). Four additional families had mutations at codon 24 (GGT----GGA), codon 26 (GAG----AAG), IVS-II-654 (C----T) and codon 110 (GTG----CCG), respectively. The newly discovered deletion mutation at codons 127/128, and mutations at nucleotide -31, and at codon 110 are peculiar to Japanese, and have not been found in any other ethnic group. The haplotypes of the beta-globin gene cluster were also determined. Some of the haplotypes and beta-thalassemia mutations are identical to those reported in the Chinese population. However, it is noteworthy that nearly half of the beta-thalassemia mutations were unique to Japanese.
 ...
PMID:Characterization of beta-thalassemia mutations among the Japanese. 263 67

beta-Thalassaemia major patients have chronic anaemia and since 3-4 per cent of Singaporeans carry the beta-gene, prenatal diagnosis is essential. We evaluated the amplification refractory mutation system (ARMS) technique as a routine test for prenatal diagnosis of beta-major. Six mutations along the beta-gene were studied--41-42 (-TCTT), IVSII #654 (C-T), 17 beta (A-T), -28 TATA (A-G), IVSI #5 (G-C), and IVSI #1 (G-T). Our results indicate that prenatal diagnosis using these mutations can be offered to 90 per cent (35/39) of our Chinese couples and 54.6 per cent (12/22) of our Malay couples at risk. Confirmation of ARMS results was carried out using allele-specific oligonucleotide hybridization. Prenatal diagnosis using ARMS was successfully carried out in nine cases which included a set of triplets and twins. The triplets were diagnosed with the beta-trait carrying the 41-42 mutation. The couple with twins possessed the #654 mutation and one twin was diagnosed with the beta-trait and the other with #654 homozygosity. Genomic sequencing of the undefined mutations in the Chinese couples revealed rarer mutations at -29 and an ATG-AGG base substitution at the initiation codon for translation. In the Malay couples, genomic sequencing detected mutations at codon 15 (TGG-TAG) and codon 26 (GAG-AAG). We conclude that ARMS with its direct detection of amplified products by gel electrophoresis provides an accurate, rapid, and simpler method for our beta-thalassaemia prenatal diagnosis programme in Singapore.
 ...
PMID:The amplification refractory mutation system (ARMS): a rapid and direct prenatal diagnostic technique for beta-thalassaemia in Singapore. 787 57

Beta-thalassemia mutations in 282 alleles of 253 unrelated individuals originating from various provinces in the south of Thailand were characterized by dot blot hybridization, specific PCR-amplification and direct DNA sequencing. It was possible to characterize the mutations in 274 (97.2%) of alleles studied. Twelve different point mutations and two different large deletions of the beta-globin gene were identified. Seven common mutations, namely 4 bp deletion at codons 41/42. IVS1 position 5 (G-C), codon 19 (AAC-AGC), codon 17 (AAG-TAG), IVS1 position 1 (G-T), position -28 (A-G) and 3.5 kb deletion, accounted for about 91.5%. The mutations at mRNA cap site + 1 (A-C) and IVS1 position 1 (G-A), previously undescribed in Thailand, were found in 1 and 2 individuals, respectively. A novel mutation of 105 bp deletion at the 5' end of beta-globin gene was detected in a family originating from this area. The knowledge from this study should be useful for planning of genetic counseling and prenatal diagnosis programs for patients with beta-thalassemia in the south of Thailand.
 ...
PMID:The spectrum of beta-thalassemia mutations in southern Thailand. 862 12


1 2 3 4 5 Next >>