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Double-strand breaks may initiate the inversion mutation causing the Hunter syndrome
K Lagerstedt1, S L Karsten, B M Carlberg
1Department of Medical Genetics, Uppsala University, Sweden.
Human Molecular Genetics
|April 1, 1997
Summary
Patients with Hunter syndrome often experience DNA inversions between the IDS gene and its pseudogene (IDS-2). This study analyzed inversion junctions, revealing high sequence identity and suggesting a double-strand break mechanism for recombination.
Area of Science:
- Genetics
- Molecular Biology
- Human Disease Genetics
Background:
- Hunter syndrome is linked to recombination events between the IDS gene and its pseudogene, IDS-2.
- This recombination results in an inversion of intervening DNA, potentially due to intrachromosomal mispairing.
Purpose of the Study:
- To investigate the mechanisms underlying the DNA inversion in Hunter syndrome patients.
- To gain insight into the homologous recombination process between the IDS gene and IDS-2.
Main Methods:
- Isolation of inversion junctions from six unrelated Hunter syndrome patients.
- DNA sequence analysis of the isolated inversion junctions.
Main Results:
- Recombination occurred within a 1 kb region with >98% sequence identity between IDS and IDS-2.
- Alternating IDS and IDS-2 sequences at one junction suggest initiation by a double-strand break in IDS intron 7.
Conclusions:
- Homologous recombination in humans may share mechanisms with Saccharomyces cerevisiae.
- Findings have practical implications for diagnosing Hunter syndrome.