RISK REVERSALS IN PREDICTIVE TESTING FOR HUNTINGTON-DISEASE

The first predictive testing for Huntington disease (HD) was based on analysis of linked polymorphic DNA markers to estimate the likelihood of inheriting the mutation for HD. Limits to accuracy included recombi nation between the DNA markers and the mutation, pedigree structure, a nd whether DNA samples were available from family members. With direct tests for the HD mutation, we have assessed the accuracy of results o btained by linkage approaches when requested to do so by the test indi viduals. For six such individuals, there was significant disparity bet ween the tests. Three went from a decreased risk to an increased risk, while in another three the risk was decreased. Knowledge of the poten tial reasons for these changes in results and impact of these risk rev ersals on both patients and the counseling team can assist in the deve lopment of strategies for the prevention and, where necessary, managem ent of a risk reversal in any predictive testing program.