Perspectives on Genetic Testing and Return of Results from the First Cohort of Presymptomatically Tested Individuals At Risk of Huntington Disease.

This qualitative study gathered opinions about genetic testing from people who received presymptomatic testing for Huntington's disease (HD) 20-30 years ago and have lived with the implications of that testing for decades. During the last section of a semi-structured interview, participants were asked open-ended questions about their opinions on the importance of autonomy in the decision to be tested for HD, whether a formal HD testing protocol is necessary, whether physician ordering for HD is acceptable without a formal protocol, whether online direct-to-consumer (DTC) genetic testing for HD is acceptable, and whether incidental/secondary findings should be returned in the context of whole exome/genome sequencing. Most-but not all-participants were in favor of an individual's right to decide whether and when to pursue HD testing, use of a formal HD testing protocol, and returning medically actionable secondary findings. However, the majority of participants were opposed not only to physician ordering and DTC HD testing in the absence of a formal protocol but also to returning a secondary finding of an expanded HD allele. This study presents the opinions of a unique and extremely well-informed cohort on issues that need to be taken into careful consideration by genetic counselors and other medical professionals who are developing genetic testing protocols, making decisions about the availability of genetic tests, and making decisions about whether and how to return incidental findings.

Differential impairment of spatial location memory in Huntington's disease.

OBJECTIVE: To determine whether a differential impairment of spatial memory exists in Huntington's disease (HD). METHODS: Patients with HD and age matched neurologically normal subjects, as well as patients with Alzheimer's disease (AD) and Parkinson's disease (PD), learned the locations of nine items on a 3 x 3 grid over as many as 10 trials. Delayed recall of the items and their spatial locations was tested. RESULTS: Patient with HD performed worse than normal subjects on all measures, and intermediate between AD and PD patients. However, they were the only subject group in whom delayed recall of spatial locations was poorer than delayed recall of object identity. This effect was independent of the severity of dementia. CONCLUSIONS: HD patients have a differential impairment in memory for object-location information. This finding may relate to the involvement of the caudate nucleus, the primary site of pathology in HD, in corticostriatal circuits linking it with parietal association cortex. It is also consistent with views of the dorsal striatum as responsible for the acquisition over trials of specific place responses.

Onset and rate of striatal atrophy in preclinical Huntington disease.

BACKGROUND: Huntington disease (HD) is characterized by striatal atrophy that begins long before the onset of motor symptoms. OBJECTIVE: To determine when striatal atrophy begins, the extent and rate of atrophy before diagnosis of motor symptoms, and whether striatal atrophy can predict when symptom onset will occur. METHODS: Caudate and putamen volumes were measured on MRI scans of 19 preclinical subjects with the HD gene expansion who were very far (9 to 20 years) from estimated onset, and on serial scans from 17 preclinical subjects, six of whom were diagnosed with HD within 5 years after the initial scan. RESULTS: Striatal volumes were significantly smaller for the subjects who were very far from estimated onset than for age-matched control subjects. Statistical models fit to the longitudinal data suggest that rate of caudate atrophy becomes significant when subjects are approximately 11 years from estimated onset and rate of putamen atrophy becomes significant approximately 9 years prior to onset. In the six incident cases, caudate and putamen were approximately one-third to one-half of normal volume at diagnosis, and caudate volume alone was able to predict with 100% accuracy those subjects who would be diagnosed within 2 years of imaging. CONCLUSIONS: Striatal atrophy begins many years prior to diagnosable HD, and assessment of atrophy on MRI may be very useful in both predicting HD onset and in tracking progression in future therapeutic trials in preclinical subjects.