Clinical validity refers to the accuracy with which a test can predict the presence or absence of the phenotype or clinical disease.
Evaluating clinical validity is quite complex as it reflects both the clinical sensitivity and specificity of the test and the penetrance of the mutations, which the test is, designed to identify.
This diagram shows a spectrum of health outcomes where one extreme is influenced almost entirely by genetic factors and the other extreme is influenced almost entirely by environmental factors.
Most common conditions, such as heart disease and diabetes, fall towards the centre, indicating both genetic and non-genetic factors influence the penetrance and expressivity (RLO) of these conditions.It is difficult to determine the clinical validity of genetic variants associated with common conditions, as both genetic and environmental factors play a role in the clinical outcome. This is the main obstacle to developing clinically useful genetic tests for these conditions.
Evidence for clinical validity will require robust epidemiologic studies. This will provide data which, in combination with analytical validity information, will allow the calculation of clinical sensitivity, clinical specificity or clinical positive and negative predictive value of a test for a particular clinical disorder in a defined population.
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