Glossary of Terms

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

Adaptive commode

A device used to assist with toileting when the individual is unable to manage unaided.

Source: 

Assisted Toileting. (n.d.). Retrieved August 8, 2019, from link.

Amyotrophic lateral sclerosis (ALS)

A group of rare neurological disorders known as motor neuron diseases. ALS is characterized by the progressive degeneration and eventual death of nerve cells in the brain, brainstem, and spinal cord. ALS presents similar signs and symptoms to CMT4J and is often referred to as Lou Gehrig’s disease.

Source: 

Amyotrophic Lateral Sclerosis. (n.d.). Retrieved October 1, 2019, from link.

Martyn, C., & Li, J. (2013, Feb.). Fig4 Deficiency: a newly emerged lysosomal storage disorder? Progress in Neurobiology. doi:10.1016/j.pneurobio.2012.11.001. Retrieved September 12, 2019, from link.

Areflexia

The absence of reflexes.

Source: 

Areflexia. (n.d.). Retrieved June 27, 2019, from link.

Autosomal

Inheritance characteristic where a gene is located on a numbered, non-sex chromosome. These are found on one of the 22 pairs of (44 total) autosomal chromosomes in a human body where DNA is stored. This is one of several ways that a trait, disorder, or disease can be passed down through families. These chromosomes are not the sex (X or Y) chromosomes.

Source: 

Shiel, W. C. (2018, December 11). Definition of Autosomal. Retrieved June 6, 2019, from link.

Autosome

Any chromosome in a cell that is not an X or Y sex chromosome. The average person has 22 pairs of autosomes (44 autosomes in total) in each cell that define the genetic make-up, or DNA, of the individual. These chromosomes store thousands of genes and they are inherited from the parents. In addition to the 22 pairs of autosomes (44 total), individuals also have one pair (2 total) sex chromosomes (X and Y in a male, and X and X in a female).

Source: 

Shiel, W. C. (2018, December 4). Definition of Autosome. Retrieved June 6, 2019, from link.

Shiel, W. C. (2018, December 11). Definition of Autosomal. Retrieved June 6, 2019, from link.

Autosome – Definition and Function of Autosomes. (2017, April 28). Retrieved June 7, 2019, from link.

Axon

Long and single nerve-cell process that usually conducts impulses away from the cell body.

Source: 

Axon. (n.d.). Retrieved June 27, 2019, from link.

B

Benign variant

When a variant has no impact on health and is recognized as a neutral variant.

Source: 

What is a variant? (n.d.). Retrieved July 1, 2019, from link.

Bilevel positive airway pressure (BiPAP)

A noninvasive breathing support device that gives ventilatory support without using an invasive artificial airway (endotracheal tube or tracheostomy tube).

Source: 

Noninvasive Ventilation. (2018, October 22). Retrieved August 8, 2019, from link.

C

Charcot-Marie-Tooth (CMT)

The most common inherited motor and sensory neuropathies, composed of a group of pathologically and genetically distinct subtypes ranging from slowly to rapidly progressive disease. CMT is further classified based on the genetic mutation or variant involved – for instance, CMT4A, CMT4B, etc.

Charcot-Marie-Tooth 4J (CMT4J)

A rare inherited peripheral neuropathy often characterized by rapidly progressive, asymmetrical upper and lower extremity weakness, muscle atrophy leading to handicap, and respiratory issues with no available treatment. CMT4J is a recessive subtype of CMT caused by a variant, also referred to as a mutation, in the FIG4 gene.

Chronic inflammatory demyelinating polyneuropathy (CIDP)

A neurological disorder characterized by progressive weakness and impaired sensory function. It is considered the chronic counterpart of the acute disease Guillain-Barré Syndrome. CIDP is the most common misdiagnosis for patients living with CMT4J.

Source: 

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) Information Page. (n.d.). Retrieved October 1, 2019, from link.

Rajabally, Y. A., Adams, D., Latour, P., Attarian, S. Hereditary and inflammatory neuropathies: a review of reported associations, mimics and misdiagnoses. (2016). Journal of Neurology, Neurosurgery & Psychiatry. 87(10), 1051-1060. Retrieved October 1, 2019, from link.

Clinical trial

A study conducted in humans that evaluates the effectiveness, safety, and side effects of investigational products (which could include medications, treatments, and devices) that have the possibility of treating a disease in that particular patient group.

Continuous positive airway pressure (CPAP)

The most basic level of noninvasive breathing support device that gives ventilatory support without using an invasive artificial airway (endotracheal tube or tracheostomy tube).

Source: 

Noninvasive Ventilation. (2018, October 22). Retrieved August 14, 2019, from link.

Contractures

Tightening in or around a joint that occurs when muscles surrounding the joint weaken and other muscles remain strong or increase in strength to accommodate the weakness. Joint contractures are more common in the feet, ankles, hips, hands, and wrists.

D

Demographics

Statistical characteristics of a human population (for example, age or income) to help identify markets or segments.

Source: 

Demographic. (n.d.). Retrieved June 5, 2019, from link.

Demyelinating neuropathy

Refers to the loss or damage to the myelin or protective covering of the nerve tissue. This damage leads to slowed nerve impulses, causing neurological problems.

Source: 

Demyelinating disease: What can you do about it? (n.d.). Mayo Clinic. Retrieved July 1, 2019, from link.

Distal muscles

Muscles that are farther away from the torso (forearms, calves, feet, hands).

Dysarthria

A condition in which the muscles used for speech are weak or difficult to control. Dysarthria often is characterized by slurred or slow speech that can be difficult to understand.

Source: 

Dysarthria. (2018, May 18). Retrieved August 8, 2019, from link.

E

Encode

To specify the genetic instructions to make a protein.

Source: 

Encode. (n.d.). Retrieved September 11, 2019, from link.

Enzyme

A protein responsible for speeding the rate of chemical reaction in the cell of the living organism. Enzymes support a wide range of functions in an organism, as they spark chemical reactions. Enzymes work with, or interact with, substrates (the underlying surface or substance). When reacted together, the enzyme and substrate result in a new product or molecule that then separates from the original enzyme and goes on to create new reactions in the cell.

Source: 

Enzyme substrate complex. (n.d.). Retrieved June 5, 2019, from link.

Castro, J. (2014, April 26). How Do Enzymes Work? Retrieved June 5, 2019, from link.

F

FIG4

The FIG4 gene is the only gene in which pathogenic variants are known to cause CMT4J.

Source: 

Li, J. (1993). Charcot-Marie-Tooth Neuropathy Type 4J. Retrieved June 26, 2019, from link.

Fine motor control

The coordination of muscles, bones, and nerves to produce small, exact movements. An example of fine motor control is picking up a small item with the index finger (pointer finger or forefinger) and thumb.

Source: 

Fine motor control. (n.d.). Retrieved August 14, 2019, from link.

G

Genetic disease

A disorder in a person’s structural and functional state that is caused by a change, or mutation, in an individual’s DNA sequence.  This mutation may or may not be hereditary.

Source: 

What is a genetic disorder? (2014). Retrieved June 5, 2019, from link.

Gross motor control

The ability to make large, general movements, such as waving an arm or lifting a leg. This requires proper coordination and function of muscle, bones, and nerves.

Source: 

Gross motor control. (n.d.). Retrieved August 14, 2019, from link.

Guillain-Barré Syndrome (GBS)

A rare neurological disorder in which the body’s immune system mistakenly attacks part of its peripheral nervous system. GBS presents similar signs and symptoms to CMT4J, including muscle weakness.

Source: 

Rajabally, Y. A., Adams, D., Latour, P., Attarian, S. Hereditary and inflammatory neuropathies: a review of reported associations, mimics and misdiagnoses. (2016). Journal of Neurology, Neurosurgery & Psychiatry. 87(10), 1051-1060. Retrieved October 1, 2019, from link.

Martyn, C., & Li, J. (2013, Feb.). Fig4 Deficiency: a newly emerged lysosomal storage disorder? Progress in Neurobiology. doi:10.1016/j.pneurobio.2012.11.001. Retrieved September 12, 2019, from link.

H

Hereditary motor and sensory neuropathy (HMSN)

Another name for CMT, the most common inherited motor and sensory neuropathies, composed of a group of pathologically and genetically distinct types ranging from slowly to rapidly progressive disease.

I

Incidence

The rate of new (or newly diagnosed) cases of a disease.

J

Joint laxity

Refers to the looseness and instability of a joint. This looseness results in the tissues holding the joints together having hypermobility and may allow an individual to extend them easily and painlessly beyond the normal range of motion.

Source: 

Gabbey, A. E. (2017, April 24). Hypermobile Joints: Causes, Treatments, and Relief. Retrieved June 26, 2019, from link.

L

Likely pathogenic variant

A variant that was previously unreported but is likely expected to cause disease.

Source: 

What is a variant? (n.d.). Retrieved July 1, 2019, from link.

M

Multiple sclerosis (MS)

A neurological disease that disrupts communication between the brain and other parts of the body. Multiple sclerosis is characterized by muscle weakness and difficulty with coordination and balance, so some individuals living with CMT4J are first misdiagnosed with MS.

Source: 

Multiple Sclerosis Information Page. (n.d.). Retrieved October 1, 2019, from link.

Source: Martyn, C., & Li, J. (2013, Feb.). Fig4 Deficiency: a newly emerged lysosomal storage disorder? Progress in Neurobiology. doi:10.1016/j.pneurobio.2012.11.001. Retrieved September 12, 2019, from link.

Mutation

A mutation is any inherited genetic change. The term “mutation” is being replaced by the term “variant.”

Source: 

Mutation (n.d.). Retrieved September 13, 2019, from link.

Myelin

A soft white material that forms a thick layer around the axons of some neurons and is composed chiefly of lipids (such as cerebroside and cholesterol), water, and smaller amounts of protein.

Source: 

Myelin. (n.d.). Retrieved June 26, 2019, from link.

N

Natural history study (non-interventional study)

There are two types of natural history studies: prospective and retrospective. A natural history study examines a group of people who have a specific medical condition or disease or are at risk of developing one. A natural history is non-interventional and collects health information in order to understand how the medical condition or disease develops and how to possibly treat it. No treatment or investigational product is given. In a prospective study, this data collection is forward-looking and is done over time in the future. In a retrospective study, researchers review and examine factors related to an outcome in the past by looking back on past exposures and medical events.

Source: 

NCI Dictionary of Cancer Terms. (n.d.). Retrieved June 5, 2019, from link.

Pariser, A. R. Importance of natural history studies in rare diseases [PowerPoint slides]. Retrieved June 5, 2019, from link.

Nebulizer machine

A device used for breathing therapy as an easier alternative to inhalers. A nebulizer turns liquid medicine into a mist to help treat asthma.

Source: 

Goldman, R. (2018, September 29). What is a Nebulizer Machine? Overview, Uses & Function. Retrieved August 8, 2019, from link.

Nerve conduction study

Also known as a nerve conduction velocity test, this is an electrical test used to detect nerve conditions. The test electrically stimulates a nerve with one electrode, while a second electrode detects the electrical impulse and measures the amount of time it takes for the impulse to be transmitted. A decreased speed of nerve conduction may indicate nerve disease.

Source: 

Nerve conduction velocity test. (n.d.). Retrieved October 30, 2019, from link.

Neuron

A nerve cell that receives and sends electrical signals from sensory cells and other neurons over long distances within the body. These signals are sent to muscle neurons and other neurons.

Source: 

Shiel, W. C. (2018, December 27). Definition of Neuron. Retrieved June 26, 2019, from link.

Neuropathy

Nerve problem that causes pain, numbness, tingling, swelling, or muscle weakness in various parts of the body typically beginning in the hands or feet, then getting worse over time.

Source: 

NCI Dictionary of Cancer Terms. (n.d.). Retrieved June 26, 2019, from link.

Nucleus

A structure in most cells separated from the rest of the body. It controls and regulates the activities of the cell and carries genes.

Source: 

Nucleus. (2019, March 1). Retrieved June 26, 2019, from link.

P

Pathogenic variant

A change in DNA that causes disease.

Source: 

What is a variant? (n.d.). Retrieved July 1, 2019, from link.

Peripheral neuropathy

Refers to conditions that result when nerves that carry messages to and from the brain and spinal cord from and to the rest of the body are damaged.

Peroneal muscles

A group of muscles in the leg.

Prevalence

The total number of individuals in a population who have a disease or health condition at a specific period of time, usually expressed as a percentage of the population.

Proprioception

The perception based on awareness of the position of one’s body.

Source: 

Proprioception. (n.d.). Retrieved April 24, 2019, from link.

Prospective study

A natural history study that reviews subjects over a forward-looking length of time to observe for outcomes in the development of a disease.

Proximal muscles

Muscles that are located closer to the torso (neck, shoulder, biceps).

R

Retrospective study

A natural history study that reviews and examines factors related to an outcome in the past by looking back on past exposures and medical events.

S

Sensory neuropathy

Refers to nerves that provide feeling.

T

Tendon reflexes

A tendon is a tough cord or band of dense white fibrosis connective tissue that unites a muscle with another part (for example a bone) and exerts a reflex action in which a muscle is made to contract by a blow upon its tendon.

Source: 

Tendon reflex. (n.d.). Retrieved June 1, 2019, from link.

Trilogy ventilator

A respiratory device that is designed to provide ventilator support for a wide variety of patient conditions.

Source: 

Trilogy Ventilator. (n.d.). Retrieved August 8, 2019, from link.

U

Uncertain significance

A gene variant that is previously unreported and is of the type which may or may not be causative of the disorder.

Source: 

What is a variant? (n.d.). Retrieved July 1, 2019, from link.

V

Variant

A variant is a change in DNA. A variant may or may not cause disease. The following modifiers describe the variant: (i) pathogenic, (ii) likely pathogenic, (iii) uncertain significance, (iv) likely benign, or (v) benign depending on whether or not the variant causes disease. For example, a “pathogenic variant” may cause disease. The term “variant” has replaced the term “mutation.”

Source: 

Richards, S., Aziz, N., Bale, S., Bick, D., Das, S., Gastier-Foster, J., Grody, W. W., Hegde, M., Lyon, E., Spector, E., Voelkerding, K., Rehm, H. L. (2015, May). Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genetics in Medicine. 17(5), 405-24. Retrieved September 12, 2019, from link.