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Fragile X syndrome: diagnosis using highly polymorphic microsatellite markers.
R I Richards1, Y Shen, K Holman
1Department of Cytogenetics and Molecular Genetics, Adelaide Children's Hospital, North Adelaide, South Australia.
American Journal of Human Genetics
|June 1, 1991
Summary
Two new microsatellite markers, VK23AC (DXS297) and VK14AC (DXS292), are closely linked to fragile X syndrome. These genetic markers are valuable for diagnosing fragile X syndrome through linkage analysis in affected families.
Area of Science:
- Genetics
- Molecular Biology
- Human Genetics
Background:
- Fragile X syndrome is a significant genetic disorder.
- Accurate genetic markers are crucial for diagnosis and genetic counseling.
- The Xq27.3 region is critical for understanding fragile X syndrome.
Purpose of the Study:
- To identify and characterize novel polymorphic microsatellite markers near the fragile X site.
- To evaluate the utility of these markers for linkage analysis in fragile X families.
- To refine the genetic map of the Xq27.3 region.
Main Methods:
- Description of two microsatellite AC repeat sequences: VK23AC (DXS297) and VK14AC (DXS292).
- Two-point linkage analysis performed on 31 fragile X families.
- Construction of a multipoint linkage map using CEPH (Centre d'Etude du Polymorphisme Humain) pedigrees.
Main Results:
- VK23AC (DXS297) showed a 1% recombination frequency with a maximum lod score of 32.04.
- VK14AC (DXS292) exhibited a 7% recombination frequency with a maximum lod score of 12.87.
- DXS292 was mapped to the DXS98-DXS297 interval, 3 centimorgans (cM) proximal to DXS297.
Conclusions:
- VK23AC (DXS297) and VK14AC (DXS292) are highly polymorphic and closely linked to the fragile X site.
- These markers are effective for diagnosis by linkage in families affected by fragile X syndrome.
- The study contributes to a more detailed genetic map of the Xq27.3 region.