Clinicopathological MRI and CSF Correlates in Huntington's Disease.

Inclusion Criteria: * Native Dutch/Flemish speaker * Ability to undergo MRI scanning; * Written informed consent must be obtained from the participant. And in addition: If the participant is a pre-manifest HD gene carrier: * CAG expansion ≥ 40; * UHDRS Total Motor Score (TMS) ≤ 5; * Total Functional Capacity (TFC) = 13; * Diagnostic Confidence Score \< 4. If the participant is an early-manifest HD gene carrier: * CAG expansion ≥ 36; * Diagnostic Confidence Score = 4; * HD stage I: TFC scores between 11 and 13 inclusive. If the participant is a moderate manifest HD gene carrier: * CAG expansion ≥ 36; * Diagnostic Confidence Score = 4; * HD stage II: TFC scores between 7 and 11 inclusive. If the participant is a control subject: * Partner/spouse of a patient not at risk of HD OR sibling with genetic test results available that show a normal CAG repeat length for both HTT alleles (\<36); * No other known cognitive, neurological or psychiatric disorders. Exclusion Criteria: * Additional major comorbidities not related to HD (e.g. cardiovascular diseases, coagulopathy, hypertension, diabetes mellitus, and/or other neurological disorders); * History of severe head injury; * Status of the participant after brain surgery; * Past erythrocyte transfusions; * Use of investigational drugs or participation in a clinical drug trial within 30 days prior to study visit; * Current intoxication, drug or alcohol abuse or dependence; * Pregnancy; * Inability to understand the information about the protocol; * Severe physical restrictions (completely wheelchair dependent); * Severe chorea that, in the investigator's judgment, precludes the patient's participation in and completion of the MRI and/or lumbar puncture. * Contra-indication to MRI scanning, such as: * Claustrophobia; * Pacemakers and defibrillators; * Nerve stimulators; * Intracranial clips; * Intraorbital or intraocular metallic fragments; * Cochlear implants; * Ferromagnetic implants; * Hydrocephalus pump; * Intra-utrine device (not all types); * Permanent make-up; * Tattoos above the shoulders (not all). * Contraindications for a lumbar puncture, including: * Screening blood test results outside normal ranges(white cell count, neutrophil count, lymphocyte count, hemoglobin, platelets, Prothrombin time (PT), activated partial thromboplastin time (APTT), C-reactive protein (CRP) and serum ferritin) if only marginally decreased or increased this will be decided by the clinical PI; * Signs and symptoms of increased intracranial pressure which will be confirmed on the 7T MRI (T1 and FLAIR scan) or by a fundoscopy; * Local infections of the skin; * Use of anti-coagulant drugs within the last 14 days prior lumbar puncture.