Presymptomatic testing for huntington diseases: Recommendations for counseling.

The discovery of a genetic marker linked to the Huntington disease (HD) gene made it possible to perform presymptomatic genetic testing for this late onset disorder. The first two pilot research programs in the United States, at Massachusetts General Hospital and Johns Hopkins Hospital, began offering testing in the Fall of 1986. Twenty-three centers are now offering this testing as part of their clinical service. As testing for this and other late onset diseases becomes more widespread, it is important to assess what we have learned about offering this test to those at risk. This article presents recommendations based on the author's 5 years of experience offering presymptomatic testing for HD in order to alert counselors to the complexities of offering this type of service.