Huntington's disease (HD) is a rare, autosomal dominant, progressive neurodegenerative disorder typically becoming noticeable in middle age. It is clinically characterized by progressive involuntary movements (bradykinesia and hyperkinesia), neuropsychiatric disturbances (depression, irritability), and cognitive impairments progressing to dementia.

The striatum (caudate and putamen) is the primary area of neuronal degeneration in HD. Today, there is no validated curative treatment. HD affects approximately 6 000 patients in France and more than 30 000 individuals are considered at risk for this disease.

While the disease gene is discovered and we are capable to do a predictive genetic diagnosis for asymptomatic patients, there is no clinical or biological way to predict the age of onset or the progressive profile of patients.

One of the fundamental characteristics of this disease is its extreme variability from one patient to other both in terms of their evolution and their onset of action. Thus, this inter-individual variability severely limits the genetic counselling and complicating the neurological assessment.

Increasingly, it has been assumed that modifier genes may be the source of this inter-individual variability and that their identification could help the understanding and prediction of disease progression.

Given that the mutant protein is ubiquitous, the molecular dysfunction of neurons could be found in peripheral cells from the bloodstream and will be more accessible to investigation.

In this context, we propose to focus our research not only on biological and genetic markers but also on neuroimaging and neuropsychological markers using paradigms of time reactions or measurement of evoked potentials. We hope to identify sensitive markers of the degenerative process of Huntington's disease even when patients carrying the gene may or may not have reported the disease.

The project is centered on 2 axes:

1. identification of the genetic polymorphism which may explain the phenotypic variability seeing in Huntington's disease
2. identification of biological, genetic and imaging biomarkers that could be used as predictors of clinical progression of Huntington's disease This research is based on the existence of a well followed and well characterized cohort of patients through the Francophone Huntington Network ("RESEAU HUNTINGTON de LANGUE FRANCAISE", RHLF). Therefore, this will help to combine the clinical and biological expertise of RHLF.

Inclusion Criteria (patient):

• Voluntary patients symptomatic or asymptomatic
• Patient with a number of CAG ≥36)
• Patient who know his genetic status
• Age greater than 18 years or equal to 18 years
• Patient who provided written informed consent

Exclusion Criteria (patient):

- Deterioration of the protocol preventing the understanding of the protocol

Inclusion Criteria (control):

• Voluntary controls with no family history of huntington's disease
• Control with a number of CAG <36
• Age greater than 18 years or equal to 18 years
• Control who provided written informed consent

Exclusion Criteria (control):

- Deterioration of the protocol preventing the understanding of the protocol

Patients suffering from Huntington disease (carrying the gene) versus healthy controls