Glossary of terms
Please select a letter (in blue) below to search for a glossary term.
|
D |
I |
J |
K |
|||||||||
|
N |
O |
Q |
V |
W |
X |
Y |
Z |
Versions of a gene. Individuals have two copies of each gene called alleles. One is inherited from the mother and the other from the father.
Both eyes are affected by Retinoblastoma. This is hereditary with a 50% chance of being passed to future children (unless there is germ-line mosaicism).
Cancer is a term used for more than 100 diseases where cells are abnormal and grow in an uncontrolled way. The resulting tumour can invade and destroy surrounding normal tissues, and cells from the tumour can spread through the blood or lymph to other parts of the body.
Chromosome
A bundle of coiled DNA visible under a microscope. Humans have 22 pairs of chromosomes and two unpaired sex chromosomes.
Consent
This is the process by which a patient and/or his family learn about all of the aspects of a medical treatment /genetic testing (its benefits and risks) before agreeing to be treated/tested.
Cytogenetic Analysis
Genetic analysis at the level of a chromosome.
The surgical removal of the eyeball, leaving the eye muscles, lids and surrounding structures intact.
EUA (Examination Under Anaesthesia)
An examination of the entire area of a child's eye whilst under a general anaesthetic. EUAs are used to monitor the state of a child's eye(s). Once the eyes are mature (at around 6-7 years of age) EUAs can be replaced with eye examinations in the Ophthalmology clinic. The child must be able to cooperate fully during the eye examination for it to be as effective as an EUA.
Related to the number of tumours caused by a specific mutation.
The first ever member of a family with cancer predisposition to carry a mutation/susceptibility.
A sequence of DNA that codes for a particular protein. A unit of information that determines a specific characteristic of each individual person. Genes are the information passed on from parents to offspring.
A condition that has a hereditary component.
Germ line
A germ line mutation is carried by sperm or ova and can be transmitted to the next generation.
A mutation that can be inherited. A germ line mutation.
Hypermethylation
Extensive attachment of methyl groups to DNA at cytosine bases correlated with reduced transcription/expression of the gene.
In the context of retinoblastoma testing: loss of normal allele with only the mutant allele remaining in the tumour. This will be the allele that was inherited in genetic cases.
Genetic testing at the level of a single gene.
Mosaicism
Not all cells carry the predisposing mutation.
A permanent change in the genetic material/gene. Variations in the DNA sequence of a gene that may damage function and may cause disease.
The probability that a specific mutation will lead to cancer development.
Proband
The affected family member whose disease led to diagnosis of the family's disease/mutation. Usually the first affected person in a family.
Promoter
Region of DNA in a gene that controls expression, like a switch that turns the gene on or off.
Nerve tissue lining the back of the eye that detects light and sends information to the brain.
A rare form of cancer which causes tumours to grow on the retina of children.
RB1 Gene
The piece of DNA that can cause retinoblastoma when damaged.
Any cell which is not a germ cell (sperm/ova).
Sporadic Retinoblastoma
No other affected individuals in the patient’s family i.e. no family history.
New growth of tissue in which the multiplication of cells is uncontrolled.
Tumour Suppressor Gene
Agene which needs both copies to be damaged before cancer occurs.
One eye is affected by retinoblastoma.
Unifocal
Only one tumour found in an eye.
