All eligible participants:
a) Are 21-75 years of age, inclusive; and
b) Are capable of providing informed consent or have a legal representative authorized to give consent on behalf of the participant; and
c) Are capable of complying with study procedures, including fasting, blood sampling and lumbar puncture; and
d) Are participating in the Enroll-HD study; and
e) Will have had an Enroll-HD visit within two months of the Screening Visit.
For the Healthy Control group, participants eligible are persons who meet the following criteria:
a) Have no known family history of HD; or
b) Have known family history of HD but have been tested for the huntingtin gene CAG expansion and are not at genetic risk for HD (CAG < 36).
For the Early Pre-manifest HD group, participants eligible are persons who meet the following criteria:
a) Do not have clinical diagnostic motor features of HD, defined as Unified Huntington’s Disease Rating Scale (UHDRS) Diagnostic Confidence Score < 4; and
b) Have CAG expansion ≥ 40; and c. Have burden of pathology score, computed as (CAG – 35.5) × age, < 250.
For the Late Pre-manifest HD group, participants eligible are persons who meet the following criteria:
- Do not have clinical diagnostic motor features of HD, defined as Unified Huntington’s Disease Rating Scale (UHDRS) Diagnostic Confidence Score < 4; and
- Have CAG expansion ≥ 40; and
- Have burden of pathology score, computed as (CAG – 35.5) x age, ≥ 250.
For Early Manifest HD group, participants eligible are persons who meet the following criteria:
- Have clinical diagnostic motor features of HD, defined as UHDRS Diagnostic Confidence Score = 4; and
- Have CAG expansion ≥ 40; and
- Have Stage I or Stage II HD, defined as UHDRS Total Functional Capacity (TFC) scores between 7 and 13 inclusive.
For Moderate Manifest HD group, participants eligible are persons who meet the following criteria:
- Have clinical diagnostic motor features of HD, defined as UHDRS Diagnostic Confidence Score = 4; and
- Have CAG expansion ≥ 40; and
- Have Stage III HD, defined as UHDRS TFC scores between 3 and 6, inclusive.
For Advanced Manifest HD group, participants eligible are persons who meet the following criteria:
- Have clinical diagnostic motor features of HD, defined as UHDRS Diagnostic Confidence Score = 4; and
- Have CAG expansion ≥ 40; and
- Have Stage IV HD, defined as UHDRS TFC scores between 0 and 2, inclusive.
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