The study is a single, cross-sectional cognitive interview of FuRST 2.0, functional rating scale, administered to forty Huntington's Disease Gene Expansion Carriers (HDGECs) and potentially, their companions (the companion's participation is optional in this study). The scale will be tested as a patient reported outcome (PRO) in that the information will come directly from the HDGEC participant or the HDGEC participant together with his/her companion through self-report. The purpose is to identify real or potential comprehension or usage problems with scale items, response options, instructions and disclaimer statement, which are all components of the FuRST 2.0 scale. Through a structured cognitive interview with the HDGEC participants or the HDGEC participants together with their companions, followed by qualitative analysis, the final phrasing of the individual scale items, response options, instructions and disclaimer statement for the scale will be generated. Depending on the results of this study, an additional round of cognitive pre-testing may be required in a separate study.

Inclusion Criteria for Premanifest HDGECs:

• Identified as an active participant in Enroll-HD (participants who have completed their last onsite Enroll-HD visit within approximately 15 months)
• At least 18 years of age
• Fluent in English and had his/her primary education in English
• Able and willing to provide critical feedback (per site PI or site PI's designee discretion)
• Willing and able to provide written informed consent
• Cytosine, Adenine, Guanine (CAG) length ≥ 40
• Disease burden score (DBS) ≥ 250
• Diagnostic confidence level (DCL) ≤ 3

Inclusion Criteria for Early-manifest HDGECs:

• Identified as an active participant in Enroll-HD (participants who have completed their last onsite Enroll-HD visit within approximately 15 months)
• At least 18 years of age
• Fluent in English and had his/her primary education in English
• Able and willing to provide critical feedback (per site PI or site PI's designee discretion)
• Willing and able to provide written informed consent
• CAG length ≥ 36
• DCL= 4
• Total Functional Capacity (TFC) ≥11

Inclusion Criteria for a Companion of an HDGEC

• At least 18 years of age
• Fluent in English and had his/her primary education in English
• In his/her opinion, has sufficient interaction and knowledge of the HDGEC participant's capabilities and daily activities
• Is acceptable to the HDGEC participant and the site PI or site PI's designee
• Willing and able to provide written informed consent

Exclusion Criteria for an HDGEC/a companion of HDGEC:

• Significant cognitive or any other impairment sufficient to interfere with study associated tasks as judged by the site PI or the site PI's designee

An HDGEC: Premanifest and early-manifest HDGEC who is also a participant in Enroll-HD and meets the protocol selection criteria for the HDGEC. HDGEC participants will be recruited from English speaking Enroll-HD sites.

A Companion: A person who, in his/her opinion, has sufficient interaction and knowledge of the HDGEC participant's capabilities and daily activities, is acceptable to the HDGEC participant and the site principal investigator (site PI) or site PI's designee and meets the protocol selection criteria for the companion. The companion's participation is optional in this study.