the half of the DNA double-helix that is mostly used as a backup, but sometimes produces message molecules

one of the two copies of a gene

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

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

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

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

A natural barrier, made from reinforcements to blood vessels, that prevents many chemicals from getting into the brain from the bloodstream

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

Long strings of genes, tightly coiled into packages of DNA inside cells. Each cell’s DNA is stored as 46 chromosomes. The HD gene is on chromosome 4. Each chromosome has two copies, one inherited from each parent.

A research study involving human volunteers (also called participants) that is intended to add to medical knowledge. There are two types of clinical studies: interventional studies (also called clinical trials) and observational studies.

Very carefully planned experiments designed to answer specific questions about how a drug affects human beings

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

In experimental research for HD controls are participants who do not have the mutated gene. They can be from HD families or not

A system for editing DNA in precise ways

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

Direct stimulation of the brain using electrical impulses through tiny wires

deoxyribonucleic acid: a molecule found in the cells of all living organisms, containing the genetic information that determines traits and how an organism functions. Think of it as a blueprint or a recipe that tells the body how to develop and work, similar to a computer code. 

Double-blinded 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 measure of whether a treatment works or not.

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

A specific outcome or measurement that researchers use to assess the effectiveness or safety of a treatment. Endpoints are predefined before the trial begins and can be either primary (the main result the trial is designed to evaluate, such as improvement in symptoms) or secondary (additional outcomes of interest, such as quality of life or biomarker changes).

A type of eligibility criteria. These are reasons that a person is not allowed to participate in a clinical study.

The small fraction of our DNA that is directly used to instruct cells how to make proteins

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

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.

An approach to treating HD that uses targeted molecules to tell cells not to produce the harmful huntingtin protein

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.

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

A type of eligibility criteria. These are the reasons that a person is allowed to participate in a clinical study.

A process used by researchers to communicate to potential and enrolled participants the risks and potential benefits of participating in a clinical study.

A study in which an experimental drug or treatment is given 

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

after HD diagnosis, or when symptoms are already showing

A clinical trial design strategy in which one or more parties involved in the trial, such as the investigator or participants, do not know which participants have been assigned which interventions. Types of masking include: open label, single blind masking, and double-blind masking.

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

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

A message molecule, based on DNA, used by cells as the final set of instructions for making a protein.

Brain cells that store and transmit information

biomarker of brain health

A part of the cell containing genes (DNA)

A study in which measurements are made in human volunteers but no experimental drug or treatment is given.

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 patient registry is a type of observational study.

Small pieces of protein that signal in the body from one cell to another

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

The body’s biological response to drugs

The movement of drugs through the body

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.

Liquid component of the blood.

Prior to onset or diagnosis of movement symptoms.

A figure estimating how many people there are in a particular population who have a certain medical condition.

The person who is responsible for the scientific and technical direction of the entire clinical study.

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

The written description of a clinical study. It includes the study’s objectives, design, and methods. It may also include relevant scientific background and statistical information.

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

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

• Not yet recruiting: The study has not started recruiting participants.
• Recruiting: The study is currently recruiting participants.
• Enrolling by invitation: The study is selecting its participants from a population, or group of people, decided on by the researchers in advance. These studies are not open to everyone who meets the eligibility criteria but only to people in that particular population, who are specifically invited to participate.
• Active, not recruiting: The study is ongoing, and participants are receiving an intervention or being examined, but potential participants are not currently being recruited or enrolled.
• Suspended: The study has stopped early but may start again.
• Terminated: The study has stopped early and will not start again. Participants are no longer being examined or treated.
• Completed: The study has ended normally, and participants are no longer being examined or treated (that is, the last participant’s last visit has occurred).
• Withdrawn: The study stopped early, before enrolling its first participant.

ribonucleic acid: the chemical, similar to DNA, that makes up the ‘message’ molecules that cells use as working copies of genes, when manufacturing proteins.

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

A way of silencing genes using specially designed molecules of RNA – like DNA but made of only a single strand – that target the message molecules in cells and tell them not to make a certain protein

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

the cutting up of RNA messages, to remove non-coding regions and join together coding regions.

The organization or person who initiates the study and who has authority and control over the study.

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

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. 

Treatments

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

The name of ASO drug developed by Ionis/Roche.

A stutter in the genetic code that results in the repetition of a three ‘letter’ sequence

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

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