Glossary of DNA Testing-Related Terms
Adenine (A)
One of the four bases in DNA (abbreviated as ATGC). The other bases are thymine (T), guanine (G) and cytosine (C).
Autosomal DNA
The "non-sex" chromosomes. Humans have 23 pairs of chromosomes, the first 22 pairs are the autosomal DNA chromosomes and the 23rd pair are the sex chromosomes, known as the female X-chromosome (or mtDNA chromosome) and the male Y-chromosome.
Buccal cell
A popular way to obtain DNA for a home DNA test. Buccal cells are cheek cells, which are collected by scraping the inside of the cheek with a cotton swab.
Chromosomes
Structure found in the nucleus of a cell that contain the genes. Humans have 23 pairs of chromosomes - 22 pairs of autosomal chromosomes (autosomes) and two sex chromosomes.
CODIS (Combined DNA Index System)
An FBI database that contains autosomal DNA profiles and used in foresenics to identify people.
Cytosine (C)
One of the four bases in DNA (abbreviated as ATGC). The other bases are adenine (A), guanine (G), and thymine (T).
DNA (deoxyribonucleic acid)
DNA is a chemical found in the nucleus of cells that contains the genetic information about an individual.
DYS (DNA Y-Chromosome Segment)
DYS values are assigned to new genetic markers and maintained by the HUGO Gene Nomenclature Committee.
Gene
A portion of DNA in a specific location on a specific chromosome that contains the genetic code to make a specific protein.
Genome
The total set of genetic material in the chromosomes. The human genome is made of 23 pairs of chromosomes for a total of 46 chromosomes.
Genotype
The genetic makeup of an individual person.
Guanine (G)
One of the four bases in DNA (abbreviated as ATGC). The other bases are adenine (A), cytosine (C), and thymine (T).
Haplogroup
Haplogroups are the main branches of the human genealogical tree, which correspond to early human migrations to the various continents or distinct geographical regions.
Haplotype
Am individual's unique set of values for the genetic DNA markers tested for.
HUGO (Human Genome Organization)
The organization where newly discovered DNA markers are submitted for DYS assignment.
Marker
A specific physical location (or locus) of a gene on a chromosome. DNA testing can resolve genetics by testing for different numbers of markers.
mtDNA (mitochondrial DNA)
The genetic material found in mitochondria, a specific portion of a cell that helps produce energy. mtDNA is passed down from a mother to all her children.
Sex chromosomes
The X and Y chromosomes. Males have one X-chromosome and one Y-chromosome while females have two X-chromosomes. Sex chromosomes make up the 23rd pair of chromosomes in humans.
SNP (Single Nucleotide Polymorphism)
Changes in the DNA that happen when a single nucleotide or base (A, T, G or C) in the genome sequence is changed. A person's unique DNA profile is determined by the set of SNPs the person has.
Thymine (T)
One of the four bases in DNA (abbreviated as ATGC). The other bases are adenine (A), cytosine (C), and guanine (G).
TMRCA (Time to Most Recent Common Ancestor)
A measure of how many generations two Y-chromosomes are from a common ancestor, based on the number of mutations the two Y chromosomes differ. The more DNA markers are tested for, the more precise the number of generations.
X-chromosome
One of the two sex chromosomes. Males have a X-chromosome and a Y-chromosome while females have two X-chromosomes. A mother's X-chromosome is passed down to all her children.
Y-chromosome
One of the two sex chromosomes. Males have a X-chromosome and a Y-chromosome while females have two X-chromosomes. A father's Y-chromosome is passed down to his sons but not his daughters. As such, the Y-chromosome is used for genealogy studies since it follows a surname.
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