GLOSSARY

Alleles. Alternate gene forms or variations, which are the basis of DNA testing.

Antigens. Any biological substance that can stimulate the production of, and combine with, antibodies. Variances in human antigens can be used to identify individuals within a population.

DNA. Deoxyribonucleic acid, which contains genetic material and whose shape resembles a rope ladder that has been twisted (the double helix). An individual's DNA is unique except in cases of identical twins.

DNA profiling. The process of testing to identify DNA patterns or types. In the forensic setting, this testing is used to indicate parentage or to exclude or include individuals as possible sources of body fluid stains (blood, saliva, semen) and other biological evidence (bones, teeth, hair).

DNA typing. See DNA profiling.

DQ alpha. An area (locus) of DNA that is used by the forensic community to characterize DNA. Because there exist seven variations (alleles) of DNA at this locus, individuals can be categorized into one of 28 different DQ alpha types. Determination of an individual's DQ alpha type involves a Polymerase Chain Reaction-based test.

Electrophoresis. A technique by which DNA fragments are placed in a gel and separated by size in response to an electrical field.

Epithelial cells. Membranous tissue forming the covering of most internal surfaces and organs and the outer surface of the body.

Epithelial cell fraction. One of two products from a differential extraction that removes DNA from epithelial cells before analysis of sperm DNA can be conducted. The other product is the sperm cell reaction.

Exclusion. A DNA test result indicating that an individual is excluded as the source of the DNA evidence. In the context of a criminal case, "exclusion" does not necessarily equate to "innocence."

Forensic science. The application of a field of science to the facts related to criminal and civil litigation.

Gene. A segment of a DNA molecule that is the biological unit of heredity and transmitted from parent to progeny.

Genotype. The genetic makeup of an organism, as distinguished from its physical appearance or phenotype.

Inclusion. A DNA test result indicating that an individual is not excluded as the source of the DNA evidence. In the context of a criminal case, "inclusion" does not necessarily equate to "guilt."

Inconclusive. The determination made following assessment of DNA profile results that, due to a limited amount of information present (e.g., mixture of profiles, insufficient DNA), prevents a conclusive comparison of profiles.

Marker. A gene with a known location on a chromosome and a clear-cut phenotype (physical appearance or observable properties) that is used as a point of reference when mapping another locus (physical position on a chromosome).

Polymerase Chain Reaction (PCR). A technique used in the process of DNA profiling.

Restriction Fragment Length Polymorphism (RFLP). A technique used in the process of DNA profiling.

Secretor. A person who secretes the ABH antigens of the ABO blood group in saliva and other body fluids.