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Deletion of Huntington's disease-linked G8 (D4S10) locus in Wolf-Hirschhorn syndrome
Insights
Researchers pinpointed the G8 DNA marker, linked to Huntington's disease, to a specific region on chromosome 4. This finding advances the potential for presymptomatic testing and gene isolation for this neurodegenerative disorder.
Area of Science:
- Genetics
- Neurodegenerative Disorders
- Human Molecular Genetics
Background:
- Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder causing progressive involuntary movements and dementia, typically appearing in adulthood.
- Neuronal loss in the basal ganglia and cortex characterizes HD, with a highly penetrant gene defect.
- A DNA marker, G8 (D4S10), is known to be tightly linked to Huntington's disease and localized to chromosome 4.
Purpose of the Study:
- To regionally localize the G8 DNA marker associated with Huntington's disease.
- To refine the map position of the Huntington's disease gene.
- To facilitate the development of presymptomatic testing for Huntington's disease.
Main Methods:
- Regional assignment of the G8 DNA marker (D4S10) using DNA analysis.
- Examination of DNA from patients with Wolf-Hirschhorn syndrome.
- Utilizing partial heterozygous deletions on the short arm of chromosome 4 to pinpoint marker location.
Main Results:
- The G8 DNA marker was localized to the terminal band of the short arm of chromosome 4.
- This specific region constitutes approximately 0.5% of the total human genome.
- The precise localization was achieved by analyzing chromosomal deletions in Wolf-Hirschhorn syndrome patients.
Conclusions:
- The G8 marker's precise location on chromosome 4 provides a crucial step towards isolating the Huntington's disease gene.
- This refined mapping significantly enhances the prospects for developing a presymptomatic diagnostic test for Huntington's disease.
- The study demonstrates the utility of deletion mapping in syndromic patients for gene localization.
Abstract:
Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized by progressive involuntary movements and dementia. The symptoms of the disease, although devastating in severity, do not usually appear until the third to fourth decade of life. The gene defect is highly penetrant, and results in the loss of neurones in the basal ganglia, globus pallidus, and more diffusely in the cortex. A DNA marker, G8 (or D4S10), is tightly linked to Huntington's disease and this gene has been localized to chromosome 4 (ref. 3). The discovery of this linkage marker raises the possibility of developing a presymptomatic test for the disorder, and of eventually isolating the disease gene based on its map position. We have now regionally localized the DNA marker G8 to the terminal band of the short arm of the chromosome, a region representing approximately 0.5% of the total human genome. The assignment was made by examining DNA from patients with Wolf-Hirschhorn syndrome, a birth defect resulting from partial heterozygous deletion of the short arm of chromosome 4.