Revisiting the clinical validity of multiplex genetic testing in complex diseases

The usefulness of genetic testing to identify high-risk patients for common multifactorial diseases is subject to debate. Optimism about the public health opportunities is counterbalanced with skepticism, since genetic factors appear to play a role in only a minority of patients with complex diseases, the number of genes involved is large, and their penetrance is incomplete (Holtzman and Marteau 2000; Vineis et al. 2001).