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.