Inclusion Criteria:  Presence of the A variant of SNP3 on the same allele as the pathogenic CAG triplet expansion Ambulatory, male or female patients aged ≥25 to ≤60 years Clinical diagnostic motor features of HD, defined as Unified Huntington's Disease Rating Scale (UHDRS) Diagnostic Confidence Score = 4 UHDRS Total Functional Capacity Scores ≥9 and ≤13  Exclusion Criteria:  Malignancy or received treatment for malignancy, other than treated basal cell or squamous cell carcinoma of the skin, within the previous 5 years  Received any other study drug, including an investigational oligonucleotide, within the past 1 year or 5 half-lives of the drug, whichever is longer, with the exception of the following:  a. Received WVE-120101 or WVE-120102 within the last 3 months  Implantable CNS device that may interfere with ability to administer study drug via lumbar puncture or undergo MRI scan Inability to undergo brain MRI (with or without sedation) Bone, spine, bleeding, or other disorder that exposes the patient to risk of injury or unsuccessful lumbar puncture