Huntington's disease (HD) is a rare, inherited and progressive neurodegenerative disorder for which hallmark symptoms include movement disorders, loss of cognitive faculties and psychiatric disturbances. With the progression of the disease, patients require increasing level of medical care, caregiver support, and long-term care, which lead to substantial burden of illness. Very little data are available on the direct or indirect costs for HD. The direct medical costs of HD in the US have been summarized from retrospective commercial and Medicaid claims data analysis. The indirect and out-of-pocket costs of HD in the US have not been quantified. This study will help to bridge these gaps.

This study is a single-assessment, cross-sectional online survey administered to Huntington disease gene expansion carriers (HDGECs) and companions of HDGECs by HD stage to understand the indirect and out-of-pocket costs of Huntington's disease in the US.

The survey collects the following data from each HDGEC and companion:

1. Participant demographics (for HDGECs and companion)
2. Informal care received (for HDGECs only)
3. Out of pocket HD costs (for HDGECs and companion)
4. Current employment status (for HDGECs and companion)
5. Non-work and work care giving time that companion spends taking care of HDGEC (for companion only)
6. Work Productivity and Activity Impairment (WPAI) Questionnaire (for HDGECs and companion)

Inclusion Criteria for HDGECs:

• Identified as an active participant in Enroll-HD (participants who have completed their last on site Enroll-HD visit within approximately 15 months)
• Able to provide online or written informed consent. A LAR for HDGEC can provide written consent, if applicable
• Identified as a participant with clinically diagnosed HD and has a CAG length ≥ 40
• Site PI has access to HDGEC's medical records for the purpose of completing the Resource Utilization Questionnaire
• Able to speak and understand both verbal and written English
• Has adult onset of disease (disease symptoms manifested at age 20 years or older)
• Has access to a computer/tablet/smartphone (if compatible) and internet services

Stage classification of HDGECs:

1. Early stage HDGEC: CAG length ≥ 40; DCL = 4, TFC ≥ 11
2. Middle stage HDGEC: CAG length ≥ 40; DCL = 4, 7 ≤ TFC ≤ 10
3. Late stage HDGEC: CAG length ≥ 40; DCL = 4, 0 ≤ TFC ≤ 6

Exclusion Criteria for HDGECs:

HDGECs will be excluded from the study if they have significant cognitive or any other impairment sufficient to interfere with study associated tasks as judged by the Site PI or Site PI's designee (exceptions will be made if a companion/LAR completes the survey on their behalf).

Inclusion criteria for companions:

• Able to provide online or written informed consent
• Identified as the primary provider (unpaid) of supportive care of an HDGEC (HDGEC must be an Enroll-HD participant and have a CAG length ≥ 40 and have adult onset of disease (disease symptoms manifested at age 20 years or older))
• Able to speak and understand both verbal and written English
• Aged 21 years or older at time of survey
• Has access to a computer/tablet/smartphone (if compatible) and internet services and has the technical skills required to complete an online survey

Exclusion Criteria for companions:

Companions will be excluded from the study if they are identified as paid or salaried caregivers; however, the HDGECs for whom they care may still be included in the study.

HDGECs: Participant in Enroll-HD with clinically diagnosed HD and a cytosine, adenine, guanine (CAG) length ≥ 40, who meets the protocol inclusion criteria and none of the exclusion criteria.

Companions: Primary provider (unpaid) of supportive care for an HDGEC (this HDGEC must be an active participant of Enroll-HD Study, have a CAG ≥ 40, have an adult onset of disease (disease symptoms manifested at age 20 years or older), and a DCL=4)), who meets the protocol's companion inclusion criteria and none of the exclusion criteria.