Glossary of DNA Terms
Often technical terms can get in the way of learning about DNA relationship testing. We’ve translated common terms that are often used by doctors and researchers when discussing genetic testing to help you in understanding the most commonly used words.
(formerly known as American Association of Blood Banks) Accrediting organization for paternity testing.
The recognition by an accrediting organization that the company’s services consistently conform with the standards set by the accrediting organization.
A document or expert testimony is considered to be “admissible” when it is accepted as evidence in a judicial matter.
A sworn statement in writing made especially under oath or on affirmation before an authorized magistrate or officer.
A man who may be the biological father of a child.
Any of the variations of a gene that may occur at a given locus.
At-home (NON-LEGAL) Paternity DNA test
A test where the biological specimens are collected in a non-clinical setting without the usual chain of custody procedures. Results from an at-home collection are not intended for use in legal matters. These tests are not governed by accrediting organizations.
An autopsy sample is one which is collected by a coroner or medical examiner during the examination of a body after death. Such samples usually consist of a blood sample.
Autosomal DNA is the DNA derived from all of the chromosomes (22 pairs in total) except the sex chromosomes (X & Y). A routine STR test involves the examination of a small percentage of the total autosomal DNA. The autosomal DNA examined in a DNA paternity test is non-coding, meaning that the DNA tested is not responsible for the generation of any physical characteristics of the person.
Sometimes called Birth Father or the Natural Father. The Biological Father normally contributes 50% of his DNA to the child.
This type of sample is collected using cotton-tipped applicators that are rubbed inside a person’s mouth on the inner lining of the cheek. The samples which are collected are cheek cell samples, not saliva samples. Also known as a cheek swab.
Chain of Custody
This term refers to the paper trail showing the collection, possession, control, transfer, analysis and disposition of physical evidence. For any Legal DNA case, the Chain of Custody of the sample is of utmost importance. Therefore Bio-Gene DNA has developed strict procedures and systems to ensure that the procedures have been followed.
Chain of Custody involves procedures that apply to the following steps of a DNA test:
Identification of the tested party
Collection of specimens from the tested party
Packaging of the specimens
Shipment of the specimens
Receipt of the specimens by the DNA laboratory
Testing of specimens within the DNA laboratory
Storage of the specimens
Cheek Swab sample
Child support is a court-ordered payment by one parent to the custodial parent of a minor child after divorce or separation of the parents.
Chromosomes are long pieces of DNA present in the nucleus of cells of living beings. A human has 46 chromosomes in total with 23 from each parent.
Combined Paternity Index
The Combined Paternity Index is the product of individual paternity indices at each genetic locus tested in a paternity test. The Combined Paternity Index compares the likelihood that the tested mother and alleged father produced the child versus the likelihood that the mother and a man selected at random from the population produced the child. It is a measure of the weight of the scientific evidence obtained from the test.
Court-ready Paternity test
Commonly referred to as legal test.
Parent who has custody of the child.
Custody is a legal term used, most often in a divorce or separation, to describe who will have legal control and responsibility for a minor child. Legal custody may be granted to a single individual or to both parents (called joint or shared custody).
A deceased person.
Deoxyribonucleic Acid / DNA
A complex naturally occurring organic chemical that is found in all cells. This compound is responsible for coding the genetic information that is passed on to offspring. Its acronym is “DNA.”
Twins that are from two separately fertilized eggs. Also called Fraternal twins
Is an interpretation of the test results that the tested relationship does not exist. For example, the tested man is not the biological father of the child.
A biological sibling, parent or child of an individual.
Fraternal twins, also called dizygotic twins, occur when two separate eggs are fertizlied. Fraternal twins may be of the same sex or of two different sexes. Although unusual, it is possible that fraternal twins could have different fathers.
These are tables showing the distribution of different alleles for the same gene. These tables are established for each genetic marker tested showing the frequency of each allele. They are established for each race and the frequencies are then used to calculate paternity indices.
A gene is the fundamental unit of heredity. It can be a coding gene (one that determines a specific function or physical characteristic) or it can be non-coding. Each gene is located at a specific position (called locus) on a particular chromosome and variations of the same gene are called alleles.
In the context of a paternity test, an alleged father is “included” when he cannot be excluded as the biological father of the child. LabCorp’s paternity results provide a specific probability of inclusion.
Kinship is a connection by blood.
Legal DNA test
A “legal” test is also called a Chain of Custody or court-ready test. It is completed using DNA samples that have been collected by an unbiased third party with a documented Chain of Custody.
The plural form of locus.
The singular term for a specific location on a chromosome.
Related through one’s mother.
A test (usually DNA) to determine whether a woman is or is not the biological mother of a child.
Relating to descent through the maternal line.
Also called identical twins, monozygotic twins develop from a single fertilized egg that divides after it is fertilized into two separate embryos. Identical twins have DNA that is exactly the same. They will be the same sex and will look like each other.
The parent who does not have custody of the child in question.
A non-standard sample is a biological sample used for DNA testing that is not a cheek swab or blood sample.
A parentage test is a biological test performed to determine whether a person is the biological parent of a child.
Related through one’s father.
For an individual locus, this value is a likelihood ratio comparing the chance the tested mother and alleged father produced the child to the chance the mother and a man selected at random from the population produced the child.
A biological test performed to determine the probability that a certain man is the biological father of a child.
A biological sample taken from a person’s body. Pathology samples are often tissue samples.
Relating to descent through the paternal line.
Postmortem means after death. It can also refer to the examination of a deceased individual to determine the cause of death and will often lead to the collection of several biological samples from the deceased.
Power of Exclusion
The ability of a genetic marker system to detect a man who has been falsely accused of paternity.
In the context of paternity testing, a prenatal test is one that is conducted before the birth of a child, using an amniotic fluid sample or piece of the placenta (CVS), from the fetus.
Prior Probability (of Paternity)
The prior probability can be from 0 to 1. This is a measure of any evidence other than the test. For example, the social evidence surrounding conception. Laboratories routinely use a prior probability of 0.5, which is considered neutral. This means that the weight of the non-test evidence in favor of paternity is equal to the evidence against paternity.
In the context of paternity testing, a random man is a theoretical man, unrelated to the alleged father, to whom the DNA of the alleged father is compared.
A second-degree relative is a grandparent, grandchild, aunt, uncle, niece, or nephew.
A cheek swab sample that is collected by the party to be tested. It is usually obtained in a person’s home.
A test to determine if two or more individuals are biologically related as either full or half siblings.
STR is an acronym for Short Tandem Repeat. STRs are short sections of DNA that contain a nucleotide sequence which is repeated a number of times in certain sites on specific chromosomes. The number of repeats differs from individual to individual within the population. These sections of DNA are examined in DNA identity testing.
A surrogate mother agrees to become pregnant for the purpose of giving birth to a child for others to raise. She can be the child’s genetic mother or could have been implanted with an egg from another woman and man.
The sex chromosome associated with female characteristics in mammals. It occurs as a pair in human females and singly in human males.
The sex chromosome that is contributed by a father to his son. Y-chromosomes are only found in males.