Presymptomatic tests in Huntington's disease and dominant ataxias
Huntington's disease (HD) and dominant ataxias (SCA) represent neurodegenerative hereditary diseases dominantly transmitted for which a direct and accurate genetic test is now available for molecular confirmation and presymptomatic test. Predictive testing programs, according to published international guidelines, are available world-wide. A large number of subjects (n=165) required a predictive HD diagnosis, although only 36% completed the program flow-chart and received the final genetic result (26 had a positive, 34 negative 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 affected children over the usually reported 50%. In 4 cases, the presymptomatic diagnosis was requested by persons at-risk for SCA1 and SCA3/Machado-Joseph disease. There were no adverse events to results or both HD and SCA presymptomatic diagnoses.