Disease-causing mutations or functional polymorphisms?

Molecular genetics has infiltrated all medical disciplines and particularly the field of neuromuscular diseases. Scientists use genetic techniques who may not always aware of their restrictions and potential pitfalls. Particularly the genetic distinction between disease-causing mutations and "benign" polymorphisms can be difficult because the current standard criteria are not sufficient. Here a recently developed mathematical algorithm is given which helps to calculate the number of required healthy controls depending on the prevalence of a genetic alteration in patients. Furthermore, the genetic criteria for disease-causing mutations are extended and the importance of functional studies compared to genetic studies questioned.