Glossary Of Genetic Genealogy Terms

Genetic genealogy terms and definitions compiled and designed to be as simple and easy to understand as possible. Additional and more technical definitions are available on several other glossary websites. Many of these terms are from the DNA-NEWBIE GLOSSARY (Used with ISOGG's permission).

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Administrator
Also known as a 'Project Administrator', 'Group Project Administrator', 'Project Manager', 'Coordinator' and 'Co-Coordinator'. A volunteer who establishes a DNA study with one or multiple commercial DNA testing companies.
Admixture DNA
The non-gender chromosomes that mix or recombine. Also known as autosomal DNA.
allele
The scientific result for a marker, shown as a number.
Ancestral haplotype
The method of deducing the MRCA's haplotype by comparing matching descendants' haplotypes, and eliminating the mutations. A minimum of three lines, as distantly related as possible, is recommended for deducing the ancestral haplotype.
Ancestral state
Refers to the state of a SNP that has mutated and is shared by the most people. Example: A negative result on a SNP means it is ancestral, a positive result means it is derived.
Anthrogenealogy
A term coined by Family Tree DNA combining the words 'anthro' and 'genealogy' in reference to utilizing DNA to trace one's heritage far beyond recorded documentation.
atDNA
Acronym for Autosomal DNA.
Atlantic Modal Haplotype (AMH)
See Western Atlantic Modal Haplotype
Autosomal DNA
The non-gender chromosomes that mix or recombine. Also known as admixture DNA.
Base
The unit or building block of DNA. Adenine (A), cytosine (C), guanine, (G), and thymine (T) are the four bases in DNA. The order of bases is the sequence of DNA.
Base pair
Two bases bonded together and attached to one of the strands in the DNA double helix. Adenine always pairs with thymine, and guanine always pairs with cytosine.
Buccal cell
A type of cell found in cheek tissue inside the mouth
Chromosome
A structure found in the nucleus of a cell that contains genetic material. Humans have 23 pairs of chromosomes; 22 pairs of autosomes and one pair of sex chromosomes.
code identity number
Usually consists of the first letter of the surname project and a number. (Example: B-12). Used to protect your identity when posting results and aids in correlating test results and pedigrees.
Coding region
A region of DNA which contains genes.
Cohanim Modal Haplotype
The Y-DNA haplotype most commonly found among males with an oral tradition of Cohen ancestry.
Cohen
The Hebrew word for priest which refers to a direct male descendant of Aaron, the brother of Moses; plural: Cohanim.
Combined DNA Index System (CODIS)
The CODIS system uses marker locations in the autosomal DNA. CODIS test results are maintained in an FBI database which is used to identify people and solve crimes.
Complementary sequences
Opposing strands of DNA which bond together to form the double helix. The bases always complement one another with adenine and thymine pairing together and cytosine and guanine pairing together.
Convergence
The process of two unrelated or less related lineages changing over time to resemble one another.
Cross-over
See recombination.
CRS
Acronym for Cambridge Reference Sequence. The first mitochondrial DNA to be fully sequenced at Cambridge University in 1981. The anonymous donor of the CRS was haplogroup 'H'. Mitochondrial results are determined based upon where the results differ from the CRS.
Deoxyribonucleic acid (DNA)
A chemical consisting of a sequence of hundreds of millions of nucleotides found in the nuclei of cells. It contains the genetic information about an individual and is shaped like a double-stranded helix.
Derived state
Refers to the state of a SNP that has mutated, usually in one man, from the ancestral state and created a new haplogroup or sub-clade of a haplogroup. A positive SNP result is derived, a negative SNP result is ancestral.
DNA amplification
The production of many DNA copies from one or a few copies or fragments.
DNA replication
The process by which the DNA double helix makes a copy of itself or of a fragment of itself. It uses the old DNA as a template for the synthesis of new DNA strands. In humans, replication occurs in the cell nucleus.
DNA sequencing
The process of determining the exact order of the nucleotide bases in a segment of DNA.
DNA-NEWBIE
A DNA-Newbie is someone who is new to the field of genetic genealogy. It is also the name of a Yahoo mailing list forum sponsored by the International Society of Genetic Genealogy. http://groups.yahoo.com/group/DNA-NEWBIE
Double helix
The twisted shape DNA forms when its two strands bond together. A double helix looks like a twisting or rotating ladder.DYS - Acronym for DNA Y-chromosome Segment - The assigned number of a marker on a segment of the Y-chromosome. Example: DYS# 393
DYS
The assigned number of a marker on a segment of the Y-chromosome. Example: DYS#393
Enzyme
A protein that facilitates a specific chemical reaction by working as a catalyst.
Exact match
Two individuals with exactly the same results for all markers or regions compared.
Family Tree DNA Time Predictor (FTDNATiPTM)
A program used to calculate estimates of Time to the Most Recent Common Ancestor (TMRCA). It is the world's first calculator that incorporates mutation rates specific to each marker. This greatly increases the power and precision of estimates.
FTDNA
Family Tree DNA Testing Company
GAP
Acronym for the Group Administrator Page - This is a webpage in which a DNA Project Administrator utilizes functions such as creating a public website, generating a FTDNATiP report, etc. to assist project participants in coordinating results.
GEDCOM
Geneological Data Communications, a plain text program created for exchanging genealogical data between different genealogical programs. Family Tree DNA's 'My FTDNA' page, Y-Search and Mitosearch all contain a feature to upload a GEDCOM for pedigree comparisons to matches.
Gene
A segment of DNA which contains the genetic code to make a certain protein or part of a protein.
Generation
The number of years between the birth of the parents and the birth of their children. Different studies use different numbers of years per generation. Family Tree DNA uses 25 years.
Genetic cousins
Individuals whose Y-DNA or mtDNA test results match one another.
Genetic distance
The number of differences, or mutations, between two sets of results. A genetic distance of zero means there are no differences in the results being compared against one another (exact match).
Genetic Genealogy
The latest tool for genealogists utilizing DNA to aid genealogical research.
Genetics
The study of genes and heredity; the study of DNA.
Genographic Project
A five-year scientific genetics project launched in 2005 to study and map human migratory patterns. The project offers a 12-marker Y-chromosome or HVR1 mtDNA test for public participation. Genographic participants have the option to join Family Tree DNA's database once their DNA results are in.
Genome
The entire complement of genetic material in a chromosome set. The human genome is composed of 46 chromosomes, with a total of 3 billion base pairs.
Genotype
The genetic makeup of an individual organism.
haplogroup
A group of similar haplotypes that share a common ancestor. A SNP test confirms a haplogroup. Haplogroups are assigned letters of the alphabet, and refinements consist of additional number and letter combinations, Example: R1b1. Haplogroups pertain to your deep ancestral origins dating back thousands of years.
haplogroup match
A grouping of those who share the same haplogroup to determine the deep ancestry of the participants. Men with the same haplogroup do share a common ancestor, but he lived a long time ago (think thousands and tens of thousands of years.) Haplogroup matches give you an idea of the migrations and ethnic origins of your ancestors.
haplotype
a series of alleles (markers) at specific locations on a chromosome that are transmitted together. Haplotypes are also known as signatures. A group of similar haplotypes that share a common ancestor with a SNP mutation is called a haplogroups.
HVR
Hyper Variable Region. The sections of non-coding mitochondrial DNA that are used for genealogical DNA testing.
ISOGG
International Society of Genetic Genealogy, a free society founded in 2005 for the promotion and education of genetic genealogy.
JoGG
The Journal of Genetic Genealogy - An online journal published quarterly with articles and features pertaining to genetic genealogy and anthrogenealogy. http://www.jogg.info/
Junk DNA
Slang term usually used in referring to the non-coding region of DNA on the Y-chromosome. For more about: http://www.psrast.org/junkdna.htm M
line leader
The person in the project who is responsible for co-ordinating the research and information on his branch of the family, by connecting paper trails, deciding how to include new test results, and helping resolve conflicts when they occur.
lineage
Persons whose DNA test results show that they share a recent common ancestor since the advent of surnames (circa 1100 AD).
Marker
A type of non-coding Y-chromosome DNA. The numbers designating your individual DNA segment numbers you receive with Y-chromosome DNA results. Example: 393=13. This means at marker #393, your allele value is 13.
Meiosis
The stage in which sperm and egg cells are formed. It is during this process that the autosomal chromosomes recombine and mutations occur.
Mitochondria
A specific organelle in the cell that helps it to produce energy. See also: testing kit
Mitochondrial DNA
Energy releasing organelles located in the cytoplasm of cells, which contain their own DNA. Mitochondrial DNA is passed from mother to child, but only females continue to pass on their maternal mitochondria to their children.
Mitosearch
A free public database sponsored by Family Tree DNA where mitochondrial DNA results from any testing facility may be uploaded and compared. http://www.mitosearch.org/
Modal haplotype
The most common result for each marker tested in a group of results. See also: ancestral signature.
MRCA
Acronym for Most Recent Common Ancestor.
mtDNA
Acronym for mitochondrial DNA.
mutation
A change in the DNA that occurs at random. In genetic genealogy, a mutation is usually beneficial, as mutations on the y-chromosome are often used in distinguishing different ancestral lines.
Mutation rate
The frequency with which random mutations occur.
Non-coding DNA
Also referred to as "Junk DNA", non-coding DNA has no known biological function.
non-paternity event
The genetic results of an individual do not match those of his surname, due to some event in the past, such as an unrecorded adoption, an unrecorded name change, or an infidelity.
Nuclear DNA
DNA of chromosomes found in the nucleus of the cell.
Null
A null is a value of zero on a marker. Nulls can occur due to missing genetic material on a marker, or a SNP can sometimes cause a null result. Several YSTR markers have been identified in certain families to have null results: 439, 448
personal page
Your page at FTDNA where you can list your contact information, earliest known ancestors, join additional projects, and choose how and where to compare your results.
Pherogram
For STRs, a plot which shows the length of a fragment of DNA. This allows its allele value to be measured.
Phylo-tree
Shortened term for Phylogenetic Tree - Most often used in reference to the available online diagrams connecting all Y-chromosome haplogroups. This term is also applied to DNA project diagrams created by Project Administrators utilizing specialized software.
RAO
Acronym for Recent Ancestral Origins (formerly known as REO - Recent Ethnic Origins) The number of matches you have in Family Tree DNA's database as specified by country or region. To access the RAO, Family Tree DNA clients need to click the tab on their "My FTDNA" page.
recLOH
Acronym for Recombinant Loss of Heterozygosity - When a section of DNA on a marker is missing, that marker is sometimes repaired by another marker filling in the missing DNA with its own material. This is referred to as a "recLOH event" and is usually observed with multi-copy markers like 385a and 385b, and is also common in the 464 set. The recLOH event causes the allele values to match 11-11 instead of the more common, 11-14 that you see in R1b. For more about: Recombinational Loss of Heterozygosity (recLOH)
Recombination
An event occurring during meiosis - the formation of sperm and egg cells. One chromosome from the mother and the other from the father break and trade segments with one another.
Restriction enzyme
A protein that recognizes a certain sequence of DNA and cuts the DNA at that site.
Restriction Fragment Length Polymorphism (RFLP)
See single nucleotide polymorphism.
results
A table from the testing company showing a listing of the markers that have been tested, with a number for each marker. These results are posted at FTDNA and on the Results Page of your surname DNA project.
Sex chromosome
The X- or Y-chromosome. Normally males have one X and one Y and females have two Xs.
site search
Allows you to search the entire website for a particular name or word.
SNP
Single Nucleotide Polymorphism (pronounced "snip"); a SNP test confirms your haplogroup by determining if a SNP has mutated from its ancestral state. A SNP is usually found on a different area of the Y-chromosome than where the YSTR markers are.
SNP test
Identifies which Haplogroup, or major branch of the tree, an individual belongs to, which allows the participant to use this information to consult the scientific literature to determine the geographic locations and migrations of his/her branch.
STR
Acronym for Short Tandem Repeat - See: YSTR
Sub-clade
Referring to a "branch" farther down the phylogenetic tree. Example: H3 -> '3' is a sub-clade of mitochondrial haplogroup 'H'. R1b -> '1b' is a sub-clade of Y-chromosome haplogroup 'R'. Sub-clade testing is also referred to as deep clade testing.
testing kit
The swabs sent to you by FTDNA to rub the inside of your cheek to obtain skin cells which will be tested for your DNA. See also: Mitochondria
Time to the Most Recent Common Ancestor (TMRCA)
The amount of time or number of generations since individuals have shared a common ancestor. Since mutations occur at random, the estimate of the TMRCA is not an exact number (i.e., 7 generations), but rather a probability distribution. As more information is compared, the TMRCA estimate becomes more refined.
Transmission event
The passage of genetic material from one generation to the next.
Unique Event Polymorphism (UEP)
See single nucleotide polymorphism
X-chromosome
The female gender chromosome. If a child receives one X from the father and one X from the mother, the child's gender is female.
Y-BASE
A free public database sponsored by DNA Heritage where Y-chromosome DNA results from any testing facility may be uploaded and compared.
Y-DNA phylogenetic tree
A graphic representation of the Y-DNA haplogroups according to the YCC classification. Haplogroup names and major clades are labeled and mutation names are given along the branches of the trees.
Y-Search
A free database sponsored by Family Tree DNA where Y-chromosome DNA results from any testing facility may be uploaded and compared.
YSTR
Acronym for Y-chromosome Short Tandem Repeat. The number of times the bases repeat that determines the value of the marker. Example: Thirteen repeats of the same bases equals a value of '13'.