Molecular tests for single gene disorders have become the "gold standard," surpassing in sensitivity and specificity other ancillary tests such as imaging or neurophysiologic tests. Although direct technical problems are rare for DNA tests, few outcomes studies have been reported that examine sensitivity, specificity, and usage of tests outside the setting of academic medical centers. Ethical problems of DNA testing are mainly discussed in a theoretical framework and few published studies or case reports deal with real-life situations. Among neurologists, ethical dilemmas and attempts at their resolution are communicated mainly on a verbal basis, and even then relatively little follow-up is available. The potential use of information obtained through DNA testing by other family members, employers, insurance companies, and governmental agencies deserves scientific investigation and societal discussion. A major educational effort is needed to inform patients, providers, and third parties that the presence of a particular allele in an individual is only one piece in a complex puzzle of environmental and genetic interactions that may ultimately result in disease.