Glossary

There can be quite a bit of jargon used in scientific articles. We are slowly adding words which we are asked to define or explain in more detail here to our glossary.  If you have a suggestion for a new glossary term, please send us a message on our contact page!

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Age at onset: the age develops or acquires a specific condition or symptoms of a disorder.

ASOAnti-sense oligonucleotide. These small molecules bind to RNA and prevent the production of the protein that the RNA produces.

Astrocytes: Types of glia that support neurons by providing nutrients or through other means.

Ataxia: A loss of muscular control, leading to abnormal walking, speech changes and irregular eye movements.

Ataxia scales: Scales used by clinicians and researchers to track ataxia disease progression in patients. By assigning scores to many different signs and symptoms, a patient’s disease stage and severity can be determined. The different scales have varied components and evaluate separate symptoms and clinical presentations. For more information, visit the Ataxia Study Group. These include INAS, SARA, and Klockgether.

ATXN1: Ataxin-1 (abbreviated as ATXN1) is a small molecular machine known as a protein. Its function is to guide the creation of other proteins from our DNA blueprint, making it an incredibly important indirect player in a variety of cellular processes. When the gene encoding ATXN1 undergoes a rare mutation that elongates the resulting protein, the result is SCA1.

Autosomal Dominant Inheritance: A condition that requires only one copy of a mutated gene to manifest.

Autosomal Recessive Inheritance: A condition that requires two copies of a mutated gene to manifest.

Basket cells: Inhibitory neurons that transmit information onto Purkinje cell.

Biomarker: An objective, measurable indicator of a biological process. A biomarker allows clinicians and scientists to follow biology without doing any invasive tests or performing surgery. For example, low-density lipoprotein (LDL) or ‘bad cholesterol’ is a biomarker for heart disease. Your doctor can evaluate your risk for heart disease and track whether your condition is worsening or improving by checking the levels of LDL in your blood.

Brainstem: The connection between the spinal cord and the brain. Among the many connecting fibers in this brain region, there are a host of processing centers for our most basic physiology: breathing, heart rate, etc. In SCAs, the brainstem experiences degeneration later in disease progression, which is thought to be the cause of premature death in patients.

Cerebellum: A primary area of pathology in the spinocerebellar ataxias. This brain region sits toward the back of the skull and, though small in stature, contains the majority of the nerve cells (neurons) in the central nervous system. Contains the circuits that fine-tune our movements, giving us the ability to move with precision.

Chromosome: A cellular structure that contains all genes. Humans have 23 pairs of these chromosomes. One set is maternal and the other set is paternal.

Climbing Fibers: A type of neuronal fiber which connect two types of neurons, inferior olive neurons and Purkinje cells.

Diplopia: This condition is more commonly known as double vision, where one can simultaneous perceive 2 images of a single object, displaced from each other.

DNA: DNA stands for deoxyribonucleic acid. It is a molecule made up of nucleotides that carries the genetic code in the body’s cells.

DNA sequencing: A method to look at the specific sequence of an individual’s DNA. By comparing this DNA sequence to a known reference sequence, researchers can identify small changes in specific regions of DNA.

Dysarthria: A difficulty speaking, resulting from problems controlling muscles involved in speech.

Gene: A unit of heredity made up of DNA that fully or partially controls the development of specific traits.

Genome-wide association study (GWAS): An observational study of genetic variants, called SNPs, to identify SNPs that are associated with a trait (such as disease onset).

Glia: Non-neuronal cells that primarily responsible for supporting neurons. They are divided into several different types of cells.

Immune Response: The immune system works to detect any invading pathogen or nucleic acid. While there is a lot of research on how the immune system works, researchers still do not know why some ASOs trigger an immune response, and what the mechanism is that causes an ASO-mediated immune response.

Ion channel: A protein complex which allows movement of electrically charged molecules (ions) in and out of cell membranes, like though in nerve cells.

Laser Capture Microdissection (LCM): A technique to cut out a certain cells type of interest from a tissue sample. It is a dissection on a microscopic level.

Mild aspiration: Entry of food, drink, stomach contents or secretions into the respiratory tract.

Messenger RNA (mRNAs): the RNA molecules that ‘translate’ the genetic code from DNA so that proteins can be built based on that code.

Mouse Model: A type of animal model with specific characteristics that allow for the study of various aspects of a human disease/condition.

Neuron: a specialized cell type of the nervous system whose role is to transmit electrical signals.

Nystagmus: A condition involving the loss of eye movement control.

Oxidative stress: A type of disturbance in the normal functioning of a cell caused by an imbalance in the levels of reactive oxygen species. These oxygen species are produced as a normal byproduct of cellular metabolism and are usually cleared by the cell without much trouble. When cells are unable to sufficiently clear reactive oxygen species, these molecules begin to accumulate and cause damage to components that form a cell’s critical structures, such as lipids, proteins, and DNA. As we age, our cells naturally become less efficient at clearing reactive oxygen species and the level of oxidative stress we experience increases.

Patient fibroblasts: Fibroblasts are connective tissue cells. These cells can be taken from patients with diseases (usually by a cheek swab or small skin biopsy) and cultured in the laboratory. This allows researchers to study the disease in a human context, and to see how the cells respond to different therapeutics. The benefit of using human fibroblasts is that scientists can study the disease in human cells, which can sometimes respond differently than mouse cells to different diseases. Working with mouse models is advantageous because it lets researchers see how a disease can affect the brain when all cell-types are working together, which is something that can’t be done with human fibroblasts. Using mouse models of disease and human fibroblasts together can address these potential problems.

Penetrance: The proportion of individuals carrying a particular genetic variant that also show the characteristic phenotype.

Polyglutamine Expansion Disease / CAG-repeat diseases: A family of diseases caused by an expansion of glutamine amino acids in certain proteins.

In about 60 of our genes, there is a DNA code that instructs cells to make small molecular machines (known as proteins) that have large, repeating chemical structures. These structures are made up of the chemical glutamine. While glutamine repeats serve a valuable function under normal conditions, they can also be quite unstable. In polyglutamine expansion disorders, the process of copying these repeating DNA codes becomes disrupted sometime early in development, causing an out-of-control expansion of the number of glutamines that a protein is supposed to contain. Because each gene has a different function, the gene in which a polyglutamine expansion occurs determines which disease a patient has – for example, SCA1 occurs from a polyglutamine expansion in the ATXN1 gene, while Huntington’s disease occurs from a polyglutamine expansion in the IT15 gene.

Protein: A molecule determined by a specific sequence of DNA. These molecules have a specific function in cells, tissues, and organs.

Protein Kinase C (PKC): A protein that regulates function and survival of cells by phosphorylating proteins in the cells.

Purkinje Neurons: A type of neuron in the cerebellum. They are some of the largest cells in the brain. They help regulate fine movement.  Purkinje cell loss/pathology is a common feature in cerebellar ataxia.

Reactive Oxygen Species (ROS): Reactive molecules that contains oxygen and interact with other molecules in cells. A higher than normal level of these reactive molecules is a source of stress in cells.

Rotarod: The rotarod is a technique that has been used for decades to test motor performance in mice and rats. Researchers place the animal on a rotating cylinder and record how long it takes for the animals to fall off as the rotation speed is gradually increased. The higher the mouse/rat’s motor performance, the longer they will be able to stay on.

RNARibonucleic acid. This molecule copies the information encoded in genes (which are made of DNA) and functions as a blueprint for making proteins in a cell.

Single Nucleotide Polymorphism (SNPs): A variation in a single base-pair of DNA.

Spinocerebellar ataxia (SCA): A group of heritable, adult-onset degenerative disorders. Please see our What is Ataxia? page for more details.

Staufen1 (STAU1): a protein that binds to specific messenger RNAs and delivers them to protein machinery for degradation.

Stem cells: early developmental cells that duplicate themselves many times and give rise to many different cell types.

Stress granules: membrane-less globules in a cell that contain/protect messenger RNAs from harmful cellular stress conditions.

Transcription: The process in which the genetic information from DNAis copied into RNA, another medium for genetic information.

Transcription Factor: A protein that affect the rate of transcription, effectively turning genes off or on.

Translation: The process after transcription where RNA is converted into a protein sequence.

This page was contributed to by multiple authors and is curated by Carlos Barba.