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

Term Definition
A
B Bias Bias is where an association between an exposure and an effect does not equal the true value. Examples of how bias can be introduced into a study are in its design, the selection of the study population and how the data is collected.
C Chromatin DNA that is folded up with an array of proteins.
Chromosome Chromatin is further packaged by folding to form the entity known as a chromosome.
Chromosome abnormalities An unusual number of chromosomes in a cell and/or a structural change within one or more chromosomes such as a deletion, insertion or exchange of chromosomal material.
Cognitive Relates to the mental process involved in knowing, learning and understanding things.
Chromosome constitution The genetic constitution you are born with and which is (mostly) present in every cell of your body. For a normal human male this is 46,XY and a normal human female it is 46,XX.
Cognitive health The ability to clearly think, learn and remember. It also relates to how your brain changes as you age and what you can do to keep your cognitive function at its best.
Control group A group of people in a study who resemble the experimental group but who have not experienced the ‘event’ being studied. The same measurements are made in both the experimental and control groups to check for any differences between the two. Ideally, people in the control group should be as similar as possible to those in the experimental group, to make it as easy as possible to detect any differences due to the ‘event’ being tested.
Correlation Interdependence of two or more variable (changeable) quantities such that a change in the value of one is associated with a change in the value of the others. An example is the linear correlation between dose and effect. As you increase dose you increase the effect observed.
Cytogenetics Study of the structure, function and abnormalities of human chromosomes and, how physical changes in chromosome complement influence genetic behavior and clinical effect.
D Deoxyribonucleic acid (DNA) DNA is the molecular basis of heredity. The DNA sequence encodes the genetic information responsible for the development and functions of an organism and, allows for transmission of that genetic information from one generation to the next.

The DNA macromolecule is structured as a double-stranded helix held together by weak hydrogen bonds between purine-pyrimidine nucleotide base pairs: adenine (A) paired with thymine (T), and guanine (G) paired with cytosine (C).

Double strand break (DSB) A type of DNA damage that involves breakage of both DNA strands. This type of damage can cause the cell to die as a mechanism to prevent transmission of genetic damage. Alternatively, the DSB may repair correctly or incorrectly. Incorrect repair may lead to the formation of DNA mutations or structural chromosome aberrations.
E
F Fluorescence in situ hybridisation (FISH) The process whereby fluorescent dyes are attached to specific regions of the genome, thus aiding the identification of chromosomes and their structure.
G Genetic damage When an agent, such as ionising radiation, causes DNA damage in male or female reproductive (germ) cells, that damage can be transmitted to the next generation (their children).

Genetic damage that occurs in any of the other (somatic) cells of the body may also be transmitted to new generations but in this instance, it is passed onto somatic cells in the same person e.g. newly formed blood cells.

Genome The genetic complement contained in the chromosomes of a given organism.
Genomic instability An increased tendency for the occurrence of newly arising, non-clonal, alterations to the genome.
Genotoxic An agent that causes (usually irreversible) damage to or alteration of DNA or chromosomes.
H
I Ionising radiation Radiation with sufficient energy to eject one or more orbital electrons from an atom or molecule. Ionising radiation can be high energy electromagnetic rays ( X-rays, gamma-rays) or particulate (alpha particles, beta particles, protons).
J
K Karyotype A laboratory analysis where a person’s full complement of chromosomes are ordered according to a well-established system and examined for abnormalities.
L
M Mutation A relatively stable change in the DNA of the cell nucleus. Mutations in the germ cells of the body may lead to inherited effects in the offspring.
Matched control A control group of individuals selected to resemble an experimental group in all properties except the one under investigation.
N
O
P Psychosocial Relating to the interrelation of social factors and individual thought and behavior.
Q
R Radiation exposure Relates to the exposure to radiant energy or to the particles emitted in the transfer of radiant energy, for instance the particles and gamma rays emitted during nuclear decay.
Radiation Risk Relates to the risk that an exposure could lead to an adverse health effect in the individual exposed and/or result in heritable mutations that could lead to diseases in offspring.
Radioactivity The emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei.
Radiology The science that investigates all forms of ionising radiation in the diagnosis and treatment of disease.
Randomised Employs random selection or sampling in an experiment or procedure.
S Single strand break A type of DNA damage that involves breakage of only one DNA strand. This type of damage is easily repaired, although in some instances it could lead to the formation of a DNA mutation.
Systematic Methodical, not random.
Systematic review A review that summarises the evidence on a clearly formulated review question according to a predefined protocol, using systematic and explicit methods to identify, select and appraise relevant studies, and to extract, analyse, collate and report their findings. It may or may not use statistical techniques, such as meta-analysis.
T
U
V
W Well-being Someone’s well-being is their health and happiness.
Whole Genome Sequencing (WGS) A laboratory process that is used to determine the sequence (or code) of nearly all of an individual’s complete DNA sequence.
X
Y
Z