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NF1 microdeletion breakpoints are clustered at flanking repetitive sequences
M O Dorschner1, V P Sybert, M Weaver
1Department of Medicine, University of Washington, Medical Genetics Box 357720, Seattle, WA 98195, USA. mod@u.washington.edu
Human Molecular Genetics
|December 10, 1999
Summary
Neurofibromatosis type 1 (NF1) microdeletions cause early onset of neurofibromas. This study identifies NF1REPs as key regions involved in these deletions, suggesting a mechanism for tumor suppressor gene loss.
Area of Science:
- Genetics
- Oncology
- Molecular Biology
Background:
- Neurofibromatosis type 1 (NF1) is a genetic disorder characterized by tumor formation.
- Submicroscopic deletions involving the NF1 gene can lead to an earlier onset of cutaneous neurofibromas.
Purpose of the Study:
- To investigate the genetic mechanisms underlying NF1 microdeletions.
- To identify the critical region responsible for potentiating neurofibromagenesis in NF1 patients.
Main Methods:
- Construction of a large-insert DNA contig (BAC/PAC/YAC) at chromosome 17q11.2.
- Analysis of somatic cell hybrids from NF1 microdeletion patients.
- Breakpoint mapping within NF1REPs (NF1 Repetitive Elements).
Main Results:
- 14 out of 17 NF1 patients had 1.5 Mb deletions encompassing the NF1 gene and other loci.
- Deletions were frequently mediated by homologous recombination between NF1REPs.
- A critical region of approximately 1 Mb was narrowed down for neurofibroma potentiation.
Conclusions:
- NF1 microdeletions are often caused by homologous recombination between NF1REPs.
- NF1REP-mediated rearrangements represent a novel mechanism for tumor suppressor gene loss.
- Somatic recombination involving NF1REPs may contribute to loss of heterozygosity in NF1 tumors.