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Positional cloning utilizing genomic DNA microarrays: the Niemann-Pick type C gene as a model system
1Cancer Genetics Branch, National Human Genome Research Institute, Bethesda, MD 20892, USA. dstephan@nhgri.nih.gov
Molecular Genetics and Metabolism
|June 2, 2000
Summary
DNA microarray technology aids in identifying disease genes within large genomic regions. This method successfully located Neimann-Pick Type C (NP-C) disease gene exons and identified NPC1 based on differential gene expression.
Area of Science:
- Genomics
- Molecular Biology
- Genetic Disease Research
Background:
- Positional cloning often faces challenges in pinpointing specific mutated genes within extensive physical contigs.
- Identifying disease genes requires efficient methods for analyzing large genomic regions and gene expression patterns.
Purpose of the Study:
- To apply DNA microarray technology for identifying exons and disease genes within a defined genomic region.
- To demonstrate the feasibility of this approach using the Neimann-Pick Type C (NP-C) disease gene, NPC1.
Main Methods:
- Generated a DNA microarray using genomic fragments from a bacterial artificial chromosome (BAC) encoding NPC1.
- Used fluorescently labeled cDNA probes from NPC1 to identify exons on the array.
- Hybridized probes from differentially expressing hamster cell lines to identify the disease gene based on expression levels.
Main Results:
- Successfully identified NPC1 exons, some with intronic sequences, aiding in genomic structure determination.
- Demonstrated differential gene expression: NP-C cells (CT60) did not detect NPC1 exons, while corrected cells (911D5A13) did.
- Array technology identified NPC1 as a candidate gene through physical contig analysis and differential expression.
Conclusions:
- DNA microarray technology is effective for identifying exons and disease genes within physical contigs.
- This technique facilitates gene discovery, particularly when mutations alter mRNA levels of the disease gene.