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Genetic testing for familial hypercholesterolaemia: practical and ethical issues
S E Humphries1, D Galton, P Nicholls
1Department of Medicine, UCL Medical School, Rayne Institute, London, UK.
Insights
Genetic testing for familial hypercholesterolaemia (FH) aids in identifying individuals at high risk for early coronary artery disease (CAD). DNA tests are valuable for diagnosing FH and tracing mutations within families, especially in children.
Area of Science:
- Genetics and Cardiovascular Medicine
Background:
- Coronary artery disease (CAD) is influenced by genetics, environment, and comorbidities like diabetes and hypertension, complicating risk prediction.
- Familial hypercholesterolaemia (FH) significantly increases the risk of early CAD due to single-gene mutations.
Purpose of the Study:
- To summarize current knowledge on DNA-based tests for identifying and managing FH.
- To propose recommendations for genetic testing and future research in FH and CAD risk.
Main Methods:
- Review of current knowledge on DNA-based tests for FH.
- Formulation of recommendations for genetic testing and research priorities.
Main Results:
- DNA tests are most valuable for genetic tracing programs to identify and treat FH individuals.
- Genetic testing is appropriate for diagnosing FH in equivocal cases and detecting mutations in immediate family members, particularly children.
- Testing distant relatives for FH mutations is not currently recommended.
Conclusions:
- Genetic testing for FH is a key tool for early identification and management, especially in families with a history of premature CAD.
- Further research is needed to compare the clinical outcome prediction of genetic tests versus lipid levels for FH.
- Studies should evaluate the overall benefit of genetic testing for FH to patients, relatives, and healthcare systems.
Abstract:
Coronary artery disease (CAD) has a strong genetic component, but is also greatly influenced by environmental factors such as diet and smoking, and disorders such as diabetes mellitus and hypertension. This interaction makes prediction of CAD risk generally difficult. However, in familial hypercholesterolaemia (FH), risk of early CAD is considerably increased by the mutation of a single gene, and genetic testing may be appropriate. We summarize current knowledge concerning DNA-based tests in the identification and management of FH, and propose specific recommendations for genetic testing and further research. The major value of DNA tests for FH is in genetic tracing programs to identify and treat affected individuals. DNA testing is appropriate for: (a) diagnosis of FH when physical signs or family history are equivocal or absent (important given the increased risk of CAD associated with FH compared to other hypercholesterolaemias); (b) detection of a mutation causing FH in immediate family members (particularly children) where there is a family history of premature CAD. A positive DNA-based test for a mutation is especially useful in children, in whom plasma lipid levels may not be diagnostic. Current clinical practice is to test relatives for raised cholesterol. Testing for mutation carriers in distant relatives, although feasible, is not currently recommended. Research projects should now be started to address two issues: (i) whether genetic tests for FH better predict clinical outcome than does measurement of plasma lipid levels; (ii) whether genetic testing for FH confers overall benefit both to the patient and their relatives, and to the NHS. Answers to these questions will guide the subsequent development and implementation of genetic tests for CAD risk in general, if and when the considerably more complex genetic causes of CAD are identified.