* Inclusion Criteria:
* 18 years or older
* Provide informed consent
* Able to read and speak English
* Agree to comply with study procedures
* Inclusion criteria for the control group include:
* CAG repeat length ≤ 26.
* BMI 18.5-24.9
* Inclusion criteria for experimental group 1 include:
* BMI \< 18.5 (underweight) or significant, involuntary weight loss within the past 12 months.
* CAG repeat length 40 - 59.
* Documentation of the Clinical Diagnosis of HD with a high level of certainty (\>99% confidence) using the validated Unified Huntington's Disease Rating Scale (UHDRS).
* Stage I-III on the Functional Assessment component of the UHDRS
* Inclusion criteria for experimental group 2 include:
* BMI \> 25.0 (overweight - obesity) or BMI ≤ 25.0 with significant, unexplained weight gain within the past 12 months
* CAG repeat length 40 - 59.
* Documentation of the Clinical Diagnosis of HD with a high level of certainty (\>99% confidence) using the validated UHDRS.
* Stage I-III on the Functional Assessment component of the UHDRS
* Exclusion Criteria:
* CAG repeat length ≥ 60 to exclude participants with juvenile onset HD.
* CAG repeat length 36 - 39 to exclude participants with reduced penetrance. As this is a pilot study, we are primarily interested in participants with typical HD characteristics.
* UHDRS Functional Capacity stage ≥ 4 to exclude late-stage HD patients who may be institutionalized and receive nutrition through a feeding tube.
* Use of any of the following drugs within the last 6 months:
* System antibiotics, antifungals, antivirals, or anti-parasitics (intravenous, intramuscular, or oral)
* Corticosteroids (intravenous, intramuscular, oral, nasal, or inhaled)
* Cytokines
* Methotrexate, immunosuppressive cytotoxic agents, or chemotherapy
* Commercial probiotics ≥ 100 million CFU (fermented foods, yogurts, and other homeopathic probiotics and prebiotics do not apply)
* Use of topical antibiotics or topical steroids within the last 7 days
* History of active, uncontrolled gastrointestinal disorders or diseases, including:
* Inflammatory bowel disease
* Ulcerative colitis
* Crohn's disease
* Irritable bowel syndrome
* Infectious gastroenteritis, colitis, or gastritis
* Clostridium difficile or Helicobacter pylori infection
* Persistent or chronic constipation or diarrhea
* Acute illness with or without fever at time of sample collection
* Positive for HIV, hepatitis B, or hepatitis C
* Confirmed or suspected immunodeficient condition/state
* Major surgery of the GI tract, excluding cholecystectomy and appendectomy
* Unstable dietary history within the past month, such as elimination or significant increase of a major food group in the diet
* Recent history of chronic, excessive alcohol consumption
* Travel outside of the United States within the last 3 months
