a single-letter spelling difference in a gene. SNPs, pronounced ‘snips’, are common and most don’t change the function of the gene.

You do not know if you carry the genetic mutation for HD gene 

A standardized rating scale for function in HD, used to assess capacity to work, handle finances, perform domestic chores and self-care tasks.
Scores range from 0 to 13, with higher scores indicating better functional capacity. 

 means that neither the participant nor the clinical trial doctor can choose or know the group the participant is in until the trial is over. This approach helps to prevent bias.

A trial in which the patient and doctor know what drug is being used. Open label trials are susceptible to bias through placebo effects.

a technique that aims to treat or prevent diseases by modifying a person’s genes. It involves introducing, removing, or changing genetic material (DNA or RNA) within a patient’s cells.

A standardized neurological examination that aims to provide a uniform assessment of the clinical features of HD

The stretch of DNA at the beginning of the HD gene, which contains the sequence CAG repeated many times, and is abnormally long in people who will develop HD

the opposite of ‘mutant’. Wild-type huntingtin, for example, is the ‘normal’, ‘healthy’ protein

How well a person can handle a treatment without having serious or uncomfortable side effects.

Part of the brain that  coordinates multiple aspects of cognition, including both motor and action planning, decision-making, motivation, reinforcement, and reward system.

A type of allocation strategy in which participants are assigned to the arms of a clinical trial by chance.

a radioactive substance that binds to a specific target in the body, allowing visualization of that target’s distribution and activity

Protein builds, maintains, and replaces the tissues in your body. The building blocks of life.

Prior to onset or diagnosis of movement symptoms.

A placebo is a dummy medicine containing no active ingredients. The placebo effect is a psychological effect that causes people to feel better even if they’re taking a pill that doesn’t work.

The movement of drugs through the body

The body’s biological response to drugs

Positron emission tomography which produces detailed 3-dimensional images of the inside of the body.

Brain cells that store and transmit information

Magentic resonance imaging: A technique using powerful magnetic fields to produce detailed images and visualizes the structure of organs, tissues, and bones 

Mutant huntingtin protein. The protein produced by the faulty HD gene.

after HD diagnosis, or when symptoms are already showing

A study where each participant is looked at several times over a time period – unlike a cross-sectional study, where each participant is looked at only once

one abbreviation for the gene that causes Huntington’s disease. The same gene is also called HD and IT-15

functional MRI:As with MRI, a technique using powerful magnetic fields  but focusing on brain function by measuring and mapping changes in blood flow, revealing which areas of the brain are active during specific tasks or cognitive processes

A clear fluid produced by the brain, which surrounds and supports the brain and spinal cord.

A measure of whether a treatment works or not

A type of gene silencing treatment in which specially designed DNA molecules are used to switch off a gene

a test of any kind – including blood tests, thinking tests and brain scans – that can measure or predict the progression of a disease like HD. Biomarkers may make clinical trials of new drugs quicker and more reliable

Brain-derived neurotrophic factor: a growth factor that may be able to protect neurons in HD.

one of the two copies of a gene

Liquid component of the blood.

The basic unit of heredity passed from parent to child. Genes are made up of sequences of DNA and are arranged, one after another, at specific locations on chromosomes in the nucleus of cells.