Huntington's disease: psychiatric practice in molecular genetic prediction and diagnosis.

Abstract

Predictive genetic testing for Huntington's disease has been available in Cardiff since 1987 using linked genetic markers, and since 1993 using direct mutation testing, which can also be used as a diagnostic test. During this period there have been numerous referrals that have required liaison with psychiatric services at all stages of the testing programme. A series of cases was selected to highlight issues from both genetic prediction and diagnosis that are relevant to psychiatric practice and have arisen during the testing programme. Issues have been raised concerning competence to consent to testing in the context of psychotic illness; depression and suicidal ideation in test candidates; requests for testing from third parties such as psychiatrists, social services and the courts; and testing of children. As genetic testing becomes possible for more disorders the lessons learned from Huntington's disease will provide valuable guidelines for counselling.