Glossary of Common DNA Terms


In reality, no population is “100% unmixed” or completely isolated from other populations. Genes can be shared between populations due to common origins, historical invasions, or slow diffusion by local contact over many generations. The result is admixture, the entry of one type of genes into the gene pool of another type.



Variation (number of repeats) of a chemical at a certain position in the strand of DNA, also referred to as marker scores.


amino acids

The building blocks of proteins. There are 20 amino acids, each of which is coded for by three adjacent nucleotides in a DNA sequence.



Computer program containing DNA profile data for about 400 populations. Used in our DNA Fingerprint, DNA Fingerprint Plus and other autosomal ancestry analyses.


autosomal markers

Unlike Y chromosome (male ancestry) or mitochondrial (female ancestry) markers, autosomal markers are distributed throughout all your chromosomes and represent your accumulated inheritance from all your ancestors. Examples of autosomal markers are the CODIS markers used by the FBI to identify crime suspects.



Any chromosome other than a sex chromosome. Humans have 22 pairs of autosomes.



Part of a nucleotide (a building block of DNA and RNA). In DNA, the bases are adenine (abbreviated A), thymine (T), cytosine (C), and guanine (G). RNA contains uracil (U) instead of thymine.



Type of mutation, or SNP (Single Nucleotide Polymorphism), in your genetic material whose analysis can show experts where your distant ancestors originated in prehistory, also what percentage of Caucasian, African, Asian and American Indian you are.



The field of biology specializing in developing hardware and software to store and analyze the huge amounts of data being generated by life scientists.


Cambridge Reference Series

The mitochondrial DNA sequence of a British man named Anderson, used since 1981 as a comparison with others’ sequences. Differences from it are considered mutations (for instance a C instead of T at a certain position). Abbreviated CRS, or rCRS (revised).






A cellular structure containing genes. Chromosomes are composed of DNA and proteins. Humans have 23 pairs of chromosomes in each body cell, one of each pair from the mother and the other from the father. The 23rd chromosome pair in males is the sex chromosome and contains an X and a Y. It is the Y chromosome (Ycs) that determines the male gender. The Y chromosome has the unique property of being passed virtually unchanged from generation to generation (only from one male to another male). This means that a man and all his sons will have the same Y chromosome. Likewise, he will have the same Y chromosome as his father and grandfather and so one. Therefore, one’s profile, or haplotype, not only identifies him, but is also links him to his direct paternal line (pedigree).


CODIS Markers

CODIS stands for Combined DNA Index System, showing the 14 markers that are standard for states participating in the FBI’s crime-solving database. The same set of markers is used in paternity tests and our DNA Fingerprint Test.

The 13 standard or core CODIS markers (14, in addition to AMEL, which shows sex) are:



Cohen Modal Haplotype

The gene type of Old Testament priests and their descendants.



A phenomenon whereby two similar genetic profiles are independently produced in unrelated populations. A coincidental match without historical significance. An example is the Atlantic Modal Haplotype, which occurs in equally high frequencies in Northwest Spain and Ireland, the reason being that both of these geographical locations lie on the margins of Europe and experienced similar genetic drift. Another example is the resemblance of East Asian DNA to Native American, conceivably due to a common deep ancestry shared by the two peoples tens of thousands of years ago.



The control, or reference series, region of mitochondrial DNA, consisting of four segments, including HVR1 and HVR2.


DNA Profiling

Also known as DNA fingerprinting and forensic DNA typing. A technique used to differentiate between two individuals using only their DNA. It was invented by Sir Alec Jeffreys of the University of Leicester in 1985 and rapidly became popular with crime experts, who used it to match blood and other evidence to a suspect’s DNA.


double helix

The shape that two linear strands of DNA assume when bonded together



The European Netowrk of Forensic Science Institutes


European Union

Multinational confederation of 27 European countries formed in 1992


familial Mediterranean fever (FMF)

fingerprint, DNA

An individual’s genetic signature as expressed in a certain set of markers, usually the CODIS markers. Used in our DNA Fingerprint Test and DNA Fingerprint Plus.



An inheritable segment of the DNA molecule that contains information for making a protein or performing some function such as passing a genetic disorder or conferring longevity. Genes can be discontinuous across a strand of DNA.


gene frequency

the relative occurrence of a particular allele in a population


genetic code

The language in which DNA’s instructions are written. It consists of triplets of nucleotides, with each triplet corresponding to one amino acid in a protein or to a signal to start or stop protein production.


genetic counseling

genetic counselors

genetic disorders

genetic profile

Your unique set of numerical values or scores (alleles, mutations or STR repeats) at defined sites on your DNA (markers)



The scientific study of genes and heredity of how particular qualities or traits are transmitted from parents to offspring.



All of an organism’s genetic material.


genotype, ethnotype

The genetic makeup of an organism, as characterized by its physical appearance or phenotype


haplogroup (female)

Mitochondrial haplogroups are female lineages in the world family tree. Each goes back to an a single ancient founder. Vincent Macaulay in his update to Richards et al. (1999) lists the characteristic mutations identifying haplogroups L, M, C, D, E, G, Z, N, I, A, W, X, R, B, F, Y, JT, J, T, U, and K. Brian Sykes coined names for the Seven Daughters of Eve for European female haplogroups or lineages.


haplogroup (male)

If a haplotype can be thought of as a twig on the family tree, a haplogroup is the branch. Each of these is linked to a continent (such as Europe) and often to a race (such as Asian). Common haplogroups are R1a, R1b, J, E3a, E3b, and I. See also Conversion Chart for Male Haplogroups.



A haplotype can be thought of as a twig on the family tree.



It is a person’s set of values for the markers that have been tested. Two individuals that match on all markers but one, have two distinct haplotypes (one-step mutation). Matching another person’s exact haplotype indicates you are genetic cousins and have a common ancestor. Haplogroups are the branches, and can be either male (based on ancient fathers’ Y chromosomes) or female (based on ancient mother’s mitochondrial DNA). They are the descents or mega-families that characterized early human migrations. These are normally associated with geographical regions. The origins of male haplotypes are measured in hundreds of years, whereas those of female haplotypes go back thousands. Examples of male haplogroups: R1b (Western Atlantic European), I (northern Europe), J (Jewish, Middle Eastern).



the transmission of characteristics from one generation to the next by genes




Human Genome Project


Hypervariable region 1 of the D-loop of mitochondrial DNA ranges from nucleotide position (np) 16001-16570.Our genomics lab looks at the range extending from np 16020 to np 16569 and determines its base (A, G, C or T) for our mitochondrial DNA ancestry tests. Also known as HVS1, or Hypervariable Segment 1.



Hypervariable Region 2 is an extended part of the control, or reference, series of nucleotides in the D-loop, each containing one of the four bases, A, C, T or G. Study the Cambridge Reference Series. Our lab examines HVR2 from 1 to 390. All these loci are tested for our premium mitochondrial tests. The addition of HVR2 to HVR1 gives you twice as much detail for matches. Also called HVS2, or Hypervariable Segment 2.



Within the same narrow sub-population. One example of in-group marriage practices is found in European royal families.



branches on the family tree: either male (Y chromosomal) or female (mitochondrial)


linkage disequilibrium

association of a particular gene with a particular family inheritance




match (autosomal)

Seeming to have the same markers as another person, expressed as a very low Random Match Probability or very high Match Likelihood. The polymorphisms displayed at each locus on the DNA are by themselves very common. Typically, each allele (variation) will be shared by around 5-20% of individuals. When looking at multiple markers, it is the unique combinations of these polymorphisms to an individual that makes DNA Fingerprinting such a good identification tool. The more markers that are tested the more discriminating the test becomes, and the higher the relief in population matches. The standard number is 16.


medical terms


An ethnic group found primarily in the lower Appalachian mountains of Kentucky, Tennessee, Virginia, North Carolina and Alabama. Often termed a “triracial isolate” because of its unique mixture of Native American, European and African families. Bibliography


Mendelian inheritance


Repeated sequence of chemicals. Different numbers of repeats produce one’s alleles, or DNA test scores.



DNA sequences located outside the nucleus of each cell. An exact copy is passed by a mother to her children, making it possible to trace maternal descents.


Mitochondrial Eve

mitochondrial migrations

Spread of female lineages as determined by mitochondrial haplogroups out of Africa into the other continents. See World Migrations Map.



The study of similarities and differences in the anatomy or appearance of humans



A sequencing approach that uses several pooled samples simultaneously, greatly increasing sequencing speed and lowering the cost of DNA testing.



A change in a DNA sequence, either spontaneous within a generation or inherited, sometimes from a very distant ancestor. Mutations usually do not affect our health or cause any differences in our appearance. In other words, they are not genes proper and do not “code” for new proteins. Even though they are non-coding genes, though, they are useful in tracing lineages.


non-coding DNA

Also known as “junk DNA” (although recent research casts doubt on the supposition there is any DNA that does not perform a function, if only as a holding place).



A building block of DNA or RNA. It includes one base, one phosphate molecule, and one sugar molecule (deoxyribose in DNA, ribose in RNA).







The polymerase chain reaction, a quick and easy method for generating unlimited copies of any fragment of DNA. Used to multiply your sample for lab processing.





The general appearance of a person without reference to its underlying or scientific characteristics; in the past, associating appearance with a person’s character.



profile frequency

Chance of a random match for your profile (that is, it seems identical to another person).


Random Match Probability

The odds that another human being would have your exact DNA Fingerprint or genetic profile, or that the match is a mere coincidence. Expressed as, for instance, 1E+21, in other words 1 followed by 21 zeros, that is, a 1 in 1,000,000,000,000,000,000,000 (sextillion) chance that such a coincidence would occur.





Determination of the order of nucleotides (base sequences) in a DNA molecule.


sex chromosomes

Chromosomes that are different in the two sexes and involved in sex determination. Males receive XY, females XX.




pronounced “snip”: single nucleotide polymorphism



Short Tandem Repeat DNA Internet Database, created by John M. Butler and Dennis J. Reeder at the National Institute for Standards and Technology Biotechnology Division


test range

Different studies of mitochondrial DNA look at different ranges of nucleotide positions, many reporting only HVR1 mutations. The position 16519 is rarely included in published studies. Richards et al. 2000 generally includes only 16090-16365.


Y chromosomal markers

DNA Testing Systems uses a 44 Y-STR locus standard for male DNA tests. On a minimal basis, these results allow us to search the YHRD and form a picture of the geographical distribution and origin of your wider haplotype and its neighbors. On a more extended basis, this optimal number of markers lets us find potential matching male relatives you can correspond with in Ysearch and compare genealogical notes.