Glossary of Terms

Accuracy
A paternity test is considered accurate when proper procedures are followed to ensure that the results of the test are correct. At Paternity Answers, each sample is independently tested two times and the data are compared for consistency before reporting. The test results, reported as allele sizes, are objective measurements and are reliable, reproducible, and accurate.

Chain of Custody
The chain of custody refers to the specimen collection and documentation process that assures tested parties in a paternity test (and any judicial officials) that specimens were collected by a neutral party, were labeled properly, and were delivered untampered. The Chain of Custody that will allow patients to take the case to court if needed.

Chromosome
Chromosomes are bundles of DNA molecules found in a cell, held together by proteins. There are 46 chromosomes in humans arranged in pairs, each pair consisting of one chromosome inherited from the mother and the other from the father. There are 22 pairs of non-sex chromosomes and 1 pair of sex chromosomes (XX or XY).

CODIS
The Combined DNA Index System (CODIS) is a database containing the DNA profiles of individuals convicted of felony sex offenses and other violent crimes. The database contains only enough information to make matches; there are 13 standard markers used to profile the felons. Investigators can search through the database to try to find a match when they have a suspect's DNA.

DNA
Deoxyribonucleic acid (DNA) is a chemical substance found in cells of all living things. DNA, inherited from the biological parents, is the basis of heredity. It contains the code for all our physical attributes as well as the instructions for all functions of the body, including growth, development, and replication. DNA is composed of four different chemicals, A, T, C, and G, that function like letters in the code.

Exclusion
An exclusion result means that the DNA paternity test has revealed non-matches in the DNA profiles among the tested parties, and the biological relationship being tested is excluded (e.g. the alleged father is not the biological father).

Gene
A gene is a specific sequence in DNA located on a chromosome. Genes carry hereditary information and control transmission and expression of hereditary traits.

Heredity
Essentially, heredity is the transmission of specific characteristics (qualities and potentialities) from ancestor to descendent through the transmission of genes.

Inclusion
An inclusion result means that the paternity test has proved to a reasonable degree that a biological relationship exists among the tested parties (e.g. the alleged father is the biological father).

Loci (singular locus)
A locus indicates the position of a gene on a chromosome. We use loci to describe the genetic markers we use for paternity testing: the D16S539 marker is on the 539th locus described on chromosome 16. The letters in the marker name provide other information about the DNA molecule where the marker is found.

Maternal Lineage
Line of descent (inheritance) from a common female ancestor. Maternal lineages can be established through mtDNA testing.

Maternity
In essence, it is motherhood.

Mitochondria
Often called the "power plant" of the cell, mitochondria are found in cells outside the nucleus, and they produce energy for the cell.

Mutation
Genetic inconsistencies (mutations) occur naturally in all living organisms. Environmental agents such as UV radiation, carcinogens, and other toxic chemicals may cause these random changes in the DNA. Such mutations do not have any health or physical implications, but they may complicate the results of a paternity test. A genetic inconsistency is detected as a single mismatch between a child and the alleged parent. These results are factored into the final combined paternity index.

Nucleotide
A small molecule composed of three parts: a nitrogen base (a purine or pyrimidine), a sugar (ribose or deoxyribose), and phosphate. Nucleotides serve as the building blocks of nucleic acids (DNA and RNA).

Paternal Lineage
Line of descent (inheritance) from a common male ancestor. Paternal lineages can be established through Y-STR testing.

Paternity
In essence, it is fatherhood.

Paternity Test
A paternity test is a DNA test performed to determine the biological relationship between a child and the tested man. DNA from each individual is tested and the alleles at 15 DNA locations are identified and used to calculate a combined paternity index. Paternity tests are used as proof in obtaining child support, Social Security, and other benefits.

Standard Trio
In DNA testing, a standard trio refers to a mother, father, and child.