Adult onset neurological disorders. Predictive genetic testing.

BACKGROUND: With the rapid advances in gene discovery and genetic diagnosis, increasing numbers of hereditary adult onset neurological disorders can be diagnosed prior to the onset of symptoms. Such testing is called predictive or presymptomatic testing. OBJECTIVE: To present current practice for predictive testing for adult onset neurological disorders and the rationale behind it. DISCUSSION: Predictive testing should be undertaken in the setting of a formal counselling process both before and after results are given. Counselling incorporates genetic information and social and legal repercussions of taking a predictive genetic test. For predictive genetic testing to be possible, the causative mutation in the family must be known. The majority of those at risk of adult onset incurable neurodegenerative disorders choose not to have predictive testing.