Description:
BETA-THALASSEMIA
HEMOGLOBIN--BETA LOCUS; HBB
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Repository
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NIGMS Human Genetic Cell Repository
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| Subcollection |
Heritable Diseases |
| Class |
Mutations of the Hemoglobin Loci |
| Quantity |
25 µg |
| Quantitation Method |
Please see our FAQ |
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Biopsy Source
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Peripheral vein
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Cell Type
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B-Lymphocyte
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Tissue Type
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Blood
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Transformant
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Epstein-Barr Virus
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Sample Source
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DNA from LCL
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Race
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White
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Ethnicity
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GREEK
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Relation to Proband
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proband
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Confirmation
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Clinical summary/Case history
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Species
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Homo sapiens
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Common Name
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Human
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Remarks
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| IDENTIFICATION OF SPECIES OF ORIGIN |
Species of Origin Confirmed by Nucleoside Phosphorylase, Glucose-6-Phosphate Dehydrogenase, and Lactate Dehydrogenase Isoenzyme Electrophoresis |
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| Gene |
HBB |
| Chromosomal Location |
11p15.5 |
| Allelic Variant 1 |
141900.0348; BETA-ZERO-THALASSEMIA |
| Identified Mutation |
IVS2, G>A, +1; A splice junction mutant, G to A, at position 1 of IVS-2 was found in a Mediterranean by Treisman et al. (1982), in a Tunisian by Chibani et al. (1988), and in an American black by Thein et al. (1988). The same mutation was found by Hattori et al. (1992), who referred to the mutation as IVS-II-1 (G-A).
This is one of the earliest mutations at a 5-prime splice site to be described. In an analysis of 101 different examples of point mutations that lie in the vicinity of mRNA splice junctions and that have been held to be responsible for human genetic disease by altering the accuracy or efficiency of mRNA splicing, Krawczak et al. (1992) found that 62 were located at 5-prime splice sites, 26 at 3-prime splice sites, and 13 resulted in the creation of novel splice sites. They estimated that up to 15% of all point mutations causing human genetic disease result in an mRNA splicing defect. Of the 5-prime splice site mutations, 60% involve the invariant GT dinucleotides.
Sierakowska et al. (1996) found that treatment of mammalian cells stably expressing the IVS2-654 beta HBB gene with antisense oligonucleotides targeted at the aberrant splice sites restored correct splicing in a dose-dependent fashion, generating correct human beta-globin mRNA and polypeptide. Both products persisted for up to 72 hours after treatment. The oligonucleotides modified splicing by a true antisense mechanism without overt unspecific effects on cell growth and splicing of other pre-mRNAs. Sierakowska et al. (1996) stated that this novel approach in which antisense oligonucleotides are used to restore rather than to downregulate the activity of the target gene is applicable to other splicing mutants and is of potential clinical interest.
This mutation is frequent among patients in southern China and Thailand, accounting for 20% of beta-thalassemia in some regions. It causes aberrant RNA splicing. Lewis et al. (1998) modeled this mutation in mice, replacing the 2 (cis) murine adult beta-globin genes with a single copy of the human mutant HBB gene. No homozygous mice survived postnatally. Heterozygous mice carrying this mutant gene produced reduced amounts of mouse beta-globin chains and no human beta globin, and had a moderately severe form of beta-thalassemia. Heterozygotes showed the same aberrant splicing as their human counterparts and provided an animal model for testing therapies that correct splicing defects at either the RNA or DNA level.
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| Gene |
HBB |
| Chromosomal Location |
11p15.5 |
| Allelic Variant 2 |
141900.0348; BETA-ZERO-THALASSEMIA |
| Identified Mutation |
IVS2, G>A, +1; A splice junction mutant, G to A, at position 1 of IVS-2 was found in a Mediterranean by Treisman et al. (1982), in a Tunisian by Chibani et al. (1988), and in an American black by Thein et al. (1988). The same mutation was found by Hattori et al. (1992), who referred to the mutation as IVS-II-1 (G-A).
This is one of the earliest mutations at a 5-prime splice site to be described. In an analysis of 101 different examples of point mutations that lie in the vicinity of mRNA splice junctions and that have been held to be responsible for human genetic disease by altering the accuracy or efficiency of mRNA splicing, Krawczak et al. (1992) found that 62 were located at 5-prime splice sites, 26 at 3-prime splice sites, and 13 resulted in the creation of novel splice sites. They estimated that up to 15% of all point mutations causing human genetic disease result in an mRNA splicing defect. Of the 5-prime splice site mutations, 60% involve the invariant GT dinucleotides.
Sierakowska et al. (1996) found that treatment of mammalian cells stably expressing the IVS2-654 beta HBB gene with antisense oligonucleotides targeted at the aberrant splice sites restored correct splicing in a dose-dependent fashion, generating correct human beta-globin mRNA and polypeptide. Both products persisted for up to 72 hours after treatment. The oligonucleotides modified splicing by a true antisense mechanism without overt unspecific effects on cell growth and splicing of other pre-mRNAs. Sierakowska et al. (1996) stated that this novel approach in which antisense oligonucleotides are used to restore rather than to downregulate the activity of the target gene is applicable to other splicing mutants and is of potential clinical interest.
This mutation is frequent among patients in southern China and Thailand, accounting for 20% of beta-thalassemia in some regions. It causes aberrant RNA splicing. Lewis et al. (1998) modeled this mutation in mice, replacing the 2 (cis) murine adult beta-globin genes with a single copy of the human mutant HBB gene. No homozygous mice survived postnatally. Heterozygous mice carrying this mutant gene produced reduced amounts of mouse beta-globin chains and no human beta globin, and had a moderately severe form of beta-thalassemia. Heterozygotes showed the same aberrant splicing as their human counterparts and provided an animal model for testing therapies that correct splicing defects at either the RNA or DNA level.
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| Remarks |
Greek; B-zero-thalassemia; donor subject is homozygous for a splice junction mutation: a G>A change at position 1 in intron 2 of the HBB gene, IVS2,G>A,+1 (c.315+1G>A), which is detectable with endonuclease Hph I; no HbS/C, no deletion. |
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