Safety and Tolerability Study With VY-HTT01, in Adults With Early Manifesting Huntington's Disease

Inclusion Criteria: * Must be at least 18 years old. * Have CAGn repeat \>39. * Have diagnostic confidence score of 4 based on motor, cognitive, or behavioral symptoms. * Have a TFC score of 13 to 11. * Have stable dosing of neurological and psychiatric medications. * Capable of giving informed consent. * Able to comply with all procedures and study visits. Exclusion Criteria: * Have any significant structural or degenerative neurologic disease other than HD. * Have any chronic disability, significant systemic illness and/or, unstable medical condition, or clinical findings noted. * Have primary or secondary immune-compromise due to infections or medical conditions or chronic therapies. * Have contraindications to lumbar puncture or increased risks of bleeding upon surgery. * Started or changed dose of a concomitant CNS medication within 30 days. * Had prior neurosurgical procedures that could complicate the study procedures. * Have used any investigational therapies within 30 days prior to Screening, oligonucleotide therapies within 9 months prior to Baseline, or any prior gene therapy. * Male or female with reproductive capacity and is unwilling to use highly effective contraception for 12 months after surgery. * Have contraindications to MRI such as claustrophobia, embedded metal in the body, or known allergy or intolerance to contrast agents.