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- Karsten, Stanislav L., et al.
(författare)
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Two distinct deletions in the IDS gene and the gene W : a novel type of mutation associated with the Hunter syndrome
- 1997
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Ingår i: Genomics. - : Elsevier BV. - 0888-7543 .- 1089-8646. ; 43:2, s. 123-129
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Tidskriftsartikel (refereegranskat)abstract
- A novel mutation has been identified in a patient with the Hunter syndrome (mucopolysaccharidosis type II), in whom the disorder is associated with two distinct deletions separated by 30 kb. The deletions were characterized by Southern blot and PCR analyses, and the nucleotide sequences at both junctions were determined. The first deletion, corresponding to a loss of 3152 bp of DNA, included exons 5 and 6 of the iduronate-2-sulfatase (IDS) gene. The second deletion was 3603 bp long and included exons 3 and 4 of geneW, which is located in the DXS466 locus telomeric of theIDSgene. Both deletions are the result of nonhomologous (illegitimate) recombination events between short direct repeats at the deletion breakpoints. An interesting finding was the presence of the heptamer sequence 5′-TACTCTA-3′ present at both deletion junctions, suggesting that this motif might be a hot spot for recombination. We propose that the double deletion is the result of homology-associated nonhomologous recombinations caused by the presence of large duplicated regions in Xq27.3–q28.
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| 3. |
- Lagerstedt, Kristina, et al.
(författare)
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Double-strand breaks may initiate the inversion mutation causing the Hunter syndrome
- 1997
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 6:4, s. 627-633
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Tidskriftsartikel (refereegranskat)abstract
- We have previously shown that patients with the Hunter syndrome frequently have suffered from a recombination event between the IDS gene and its putative pseudogene, IDS-2, resulting in an inversion of the intervening DNA. The inversion, which might be the consequence of an intrachromosomal mispairing, is caused by homologous recombination between sequences located in intron 7 of the IDS gene and sequences located distal of exon 3 in IDS-2. In order to gain insight into the mechanisms causing the inversion, we have isolated both inversion junctions in six unrelated patients. DNA sequence analysis of the junctions showed that all recombinations have taken place within a 1 kb region where the sequence identity is >98%. An interesting finding was the identification of regions with alternating IDS gene and IDS-2 sequences present at one inversion junction, suggesting that the recombination event has been initiated by a double-strand break in intron 7 of the IDS gene. The results from this study suggest that homologous recombination in man could be explained by mechanisms similar to those described for Saccharomyces cerevisiae. The results also have practical implications for diagnosis of patients with the Hunter syndrome.
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- Timms, Kirsten M, et al.
(författare)
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Molecular and phenotypic variation in patients with severe Hunter syndrome
- 1997
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 6:3, s. 479-486
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Tidskriftsartikel (refereegranskat)abstract
- Severe Hunter syndrome is a fatal X-linked lysosomal storage disorder caused by iduronate-2-sulphatase (IDS) deficiency. Patients with complete deletion of the IDS locus often have atypical phenotypes including ptosis, obstructive sleep apnoea, and the occurrence of seizures. We have used genomic DNA sequencing to identify several new genes in the IDS region. DNA deletion patients with atypical symptoms have been analysed to determine whether these atypical symptoms could be due to involvement of these other loci. The occurrence of seizures in two individuals correlated with a deletion extending proximal of IDS, up to and including part of the FMR2 locus. Other (non-seizure) symptoms were associated with distal deletions. In addition, a group of patients with no variant symptoms, and a characteristic rearrangement involving a recombination between the IDS gene and an adjacent IDS pseudogene (IDS psi), showed normal expression of loci distal to IDS. Together, these results identify FMR2 as a candidate gene for seizures, when mutated along with IDS.
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