Presymptomatic testing in Huntington's disease and autosomal dominant cerebellar ataxias

Objective: To report a 7-year experience of presymptomatic testing in persons at risk for Huntington disease (HD) and to compare their characteristics and outcomes with those of persons at risk for a less disabling condition, autosomal dominant cerebellar ataxias (ADCA). Methods: The authors collected data on presymptomatic testing for HD (n = 712) and ADCA (n = 46) in 10 French centers. Results: The characteristics of applicants were similar in HD and ADCA, revealing a predominance of women, a low rate of completing the presymptomatic testing program, and a high rate of follow-up. The frequency of serious events was low (2% for HD, 5% for ADCA), but such events were also found after favorable results. Family planning was a more frequent reason for seeking presymptomatic testing in ADCA than in HD. Prenatal diagnosis was performed in only half of the pregnancies in HD carriers (n = 35) but in all of those in ADCA carriers (n = 4). Conclusion: Counseling in multistep and multidisciplinary teams is important not only for presymptomatic testing in HD but also for less disabling diseases.