Glossary

Click on any of the letters below to quickly navigate through the terms and definitions.

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Adenine (A) - one of the four nitrogenous bases found in DNA ; it pairs with thymine (T) to bind and form a base pair, an important molecular component for the structure of DNA

Antibody - a protein in the blood produced in response to the presence of antigens; it binds with foreign bodies in the bloodstream, such as bacteria, viruses, and other biological invaders

Antigen - a foreign substance or biological invader that elicits an immune response; the presence of antigens triggers the production of antibodies

Blood types - also known as the ABO system, blood types correspond with specific blood cell characteristics based on the presence or absence of certain antigens on the red blood cell surface; the 4 blood types are A, B, AB, and O

Buccal swabbing - a DNA collection process by which a bristle or cotton-like material, often similar to a large Q-tip, is used to rub the inside of the cheek; this process is painless and quick

Chain of custody DNA test - a legal term for a test that is performed to ensure the integrity of the results; typically, the results of a chain of custody test are court admissible; these tests cost more than in-home tests because of the collection and administrative procedures necessary to ensure the chain of custody is strictly followed

Child Support Enforcement Program (CSE) - a national program established in 1975 to ensure that both parents are financially responsible for a child; this program is enforced through the coordination of federal, state, local, and tribal child support agencies

Chromosome - the large macromolecule that contains DNA ; it is located in the nucleus of a cell and is typically wrapped around a histone; the human body has 23 pairs of chromosomes

Combined Paternity Index (CPI) - a common statistical result from paternity tests, representing the overall odds that a random, untested male could have the same genetic profile as the alleged father being tested; for example, if a paternity test resulted in a CPI of 300,000, this would mean that the odds that another male (not the alleged father) is the biological father of the child would be 1 in 300,000 the probability of paternity for the alleged father in this case, then, would be 99.99967%; similar values are given for maternity , siblingship , grandparentage , and genetic reconstruction tests

Cytosine (C) - one of the four nitrogenous bases found in DNA ; it pairs with guanine (G) to bind and form a base pair, an important molecular component for the structure of DNA

Deoxyribonucleic acid (DNA) - a self-replicating molecule found in all living things that serves as the blueprint for all the structures and functions of the body; DNA makes up chromosomes

Deoxyribose - the five-carbon sugar found in DNA

Disestablishment of paternity - the legal determination that a man is not the father of a child; some states have provisions for disestablishing paternity, although many courts are reluctant to break ties between fathers and children because of the emotional impact it may have on the children

Double helix model - the structure of DNA as defined by Watson and Crick ; this model has a backbone of two parallel helices, formed by sugars and phosphates, that is connected by base pairs (A-T, C-G)

Establishment of paternity - the legal determination that a man is the father of a child; this is particularly important in child support cases

Fragments - pieces of DNA ; often used for DNA testing and analysis

Gene - the hereditary unit in living organisms; each gene determines a physical characteristic or a behavior; in humans, genes are passed from parents to children

Genetics - the study of heredity in living organisms

Genotype - the genetic characteristics of an organism

Guanine (G) - one of the four nitrogenous bases found in DNA ; it pairs with cytosine (C) to bind and form a base pair, an important molecular component for the structure of DNA

Human leukocyte antigens (HLA) - proteins encoded by genes that are unique to each person; HLA have been used in the past for determining paternity

Identifiable information (adoption) - descriptive details in an adoption case that may lead to the positive identification of an adopted person, birth parent, or other birth relative; mutual consent between the adopted person and the birth family is typically required to access this information; this information frequently includes the current name and contact information of a person involved in an adoption case

Locus/loci - position or location of a gene on a chromosome

Mitochondrion/mitochondria - an organelle in the cell that is responsible for respiration and energy; it contains unique DNA that can be used for mtDNA testing

Mutation - a change in the structure of a gene; often caused by the addition, deletion, or rearrangement of a base

Non-custodial parent - the parent who does not have custody of a child, who is often required to pay child support

Non-identifiable information (adoption) - descriptive details about adopted persons and their birth relatives that are generally released to adopted persons over the age of 18 in the United States; some states charge fees for the release of this information; this information often includes:

• Date and place of the adopted person's birth

• Age and physical description of the birth parents

• Race, ethnicity, religion, and medical history of the birth parents

• Birth parents' educational and occupational status at the time of the adoption

• Reason for placing the child for adoption

• Existence of other children born to the birth parents

Nucleotide - the basic unit of all nucleic acids, including DNA ; in DNA, the nucleotides consist of a nitrogen base ( adenine , cytosine , guanine , or thymine ), a sugar ( deoxyribose ), and a phosphate group

Nucleus - the location of most genetic material in the cell; it is responsible for organizing and storing genes

Pathology - the study of diseases, especially in tissues, through forensic or laboratory diagnostic techniques

Phenotype - the physical appearance caused by the genotype of an organism

Polymerase chain reaction (PCR) - a technique for copying small fragments of DNA many times; it is one of the most common processes used in DNA testing

Power of exclusion - the power of a test to eliminate a certain percentage of the population from being biologically related to an individual; for example, if a paternity test using blood typing has a power of exclusion of 30%, only 30% of the male population could be eliminated from being the biological father of a tested child

Prenatal testing - DNA testing that is performed before a child is born; because DNA is present at the moment of conception, testing can be performed to verify biological relationships before birth; the DNA analysis is identical to testing performed after the child is born except that the child's DNA is collected through amniocentesis or chorionic villi sampling; DNA can also be collected from the umbilical cord upon the birth of the child

Probability of paternity - a statistical value for the odds that an alleged father is the biological father of a child; this value is derived from converting the Combined Paternity Index (CPI) into a percentage; probabilities of maternity , grandparentage , siblingship , twin zygosity , and relatedness are all calculated in the same way

Restriction fragment length polymorphism (RFLP) - a process by which DNA samples are cut into specific fragments of varying lengths for analysis; a child's fragments will be the same length as the fragments of his or her biological parents; similarities in fragment lengths can be used to verify other biological relationships

Rh factors - inherited antigens often found on the blood cells; some individuals have these antigens (Rh+) while others do not (Rh-); the presence of Rh factors, in conjunction with blood typing , has been used in the past to determine paternity

Ribose - a five-carbon sugar found in RNA, a molecule similar to DNA that is useful in replicating DNA

Serological test - an analysis of one's blood serum, particularly for HLA typing

Thymine (T) - one of the four nitrogenous bases found in DNA ; it pairs with adenine (A) to bind and form a base pair, an important molecular component for the structure of DNA

Transformation - a change in a cell from a normal state to a deadly state; this was significant to Griffith's and Avery's tests

Voluntary acknowledgement of paternity - a written admission of paternity, typically signed at the time of a child's birth

X-ray diffraction analysis - a laboratory technique through which the structure of a compound is observed; this process involves crystallizing the compound and exposing it to radiation to view the compound's shape; this was used by Franklin to reveal the structure of DNA

Zygote - the cell formed by the union of the sperm and the egg; the initial stage of fetal development; identical twins develop from the same zygote and are thus genetically identical