Presymptomatic tests in Huntington's disease and dominant ataxias

Huntington's disease (HD) and dominant ataxias (SCA) represent neurodegener ative hereditary diseases dominantly transmitted for which a direct and acc urate genetic test is now available for molecular confirmation and presympt omatic test. Predictive testing programs, according to published internatio nal guidelines, are available worldwide. A large number of subjects (n=165) required a predictive HD diagnosis, although only 36% completed the progra m flow-chart and received the final genetic result (26 had a positive, 34 n egative result for mutation). In 4 cases, an allele of intermediate range ( 33-34 CAGs) was found. Two of these shared the intermediate allele with an expanded repeat. In this case, we estimated the patient's risk to have affe cted children over the usually reported 50%. In 4 cases, the presymptomatic diagnosis was requested by persons at-risk for SCA1 and SCAS/Machado-Josep h disease. There were no adverse events to results of both HD and SCA presy mptomatic diagnoses.