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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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Click one of the letters above to advance the page to terms beginning with that letter.
Administrator search for term
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 search for term
The non-gender chromosomes that mix or recombine. Also known as autosomal DNA.
allele search for term
The scientific result for a marker, shown as a number.
Ancestral haplotype search for term
The method of deducing the MRCAi's haplotypei 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 search for term
Refers to the state of a SNPi 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 search for term
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 search for term
Acronym for Autosomal DNAi.
Atlantic Modal Haplotype (AMH) search for term
See Western Atlantic Modal Haplotype
Autosomal DNA search for term
The non-gender chromosomes that mix or recombine. Also known as admixture DNA.
Base search for term
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 search for term
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 search for term
A type of cell found in cheek tissue inside the mouth
Chromosome search for term
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 search for term
Usually consists of the first letter of the surname project and a number. (Example: B-12). Used to protect your identity when posting resultsi and aids in correlating test results and pedigrees.
Coding region search for term
A region of DNA which contains genes.
Cohanim Modal Haplotype search for term
The Y-DNA haplotypei most commonly found among males with an oral tradition of Cohen ancestry.
Cohen search for term
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) search for term
The CODIS system uses marker locations in the autosomal DNA. CODIS test resultsi are maintained in an FBI database which is used to identify people and solve crimes.
Complementary sequences search for term
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 search for term
The process of two unrelated or less related lineages changing over time to resemble one another.
Cross-over search for term
See recombination.
CRS search for term
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 haplogroupi 'H'. Mitochondrial resultsi are determined based upon where the results differ from the CRS.
Deoxyribonucleic acid (DNA) search for term
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 search for term
Refers to the state of a SNPi that has mutated, usually in one man, from the ancestral state and created a new haplogroupi or sub-clade of a haplogroup. A positive SNP result is derived, a negative SNP result is ancestral.
DNA amplification search for term
The production of many DNA copies from one or a few copies or fragments.
DNA replication search for term
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 search for term
The process of determining the exact order of the nucleotide bases in a segment of DNA.
DNA-NEWBIE search for term
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 Genealogyi. http://groups.yahoo.com/group/DNA-NEWBIE
Double helix search for term
The twisted shape DNA forms when its two strands bond together. A double helix looks like a twisting or rotating ladder.DYSi - Acronym for DNA Y-chromosome Segment - The assigned number of a marker on a segment of the Y-chromosome. Example: DYS# 393
DYS search for term
The assigned number of a marker on a segment of the Y-chromosome. Example: DYSi#393
Enzyme search for term
A protein that facilitates a specific chemical reaction by working as a catalyst.
Exact match search for term
Two individuals with exactly the same resultsi for all markers or regions compared.
Family Tree DNA Time Predictor (FTDNATiPTM) search for term
A program used to calculate estimates of Time to the Most Recent Common Ancestor (TMRCA)i. It is the world's first calculator that incorporates mutationi rates specific to each marker. This greatly increases the power and precision of estimates.
FTDNA search for term
Family Tree DNA Testing Company
GAP search for term
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 resultsi.
GEDCOM search for term
Geneological Data Communications, a plain text program created for exchanging genealogical data between different genealogical programs. Family Tree DNA's 'My FTDNAi' page, Y-Searchi and Mitosearchi all contain a feature to upload a GEDCOMi for pedigree comparisons to matches.
Gene search for term
A segment of DNA which contains the genetic code to make a certain protein or part of a protein.
Generation search for term
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 search for term
Individuals whose Y-DNA or mtDNAi test resultsi match one another.
Genetic distance search for term
The number of differences, or mutations, between two sets of resultsi. A genetic distance of zero means there are no differences in the results being compared against one another (exact match).
Genetic Genealogy search for term
The latest tool for genealogists utilizing DNA to aid genealogical research.
Genetics search for term
The study of genes and heredity; the study of DNA.
Genographic Project search for term
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 mtDNAi test for public participation. Genographic participants have the option to join Family Tree DNA's database once their DNA resultsi are in.
Genome search for term
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 search for term
The genetic makeup of an individual organism.
haplogroup search for term
A group of similar haplotypes that share a common ancestor. A SNP testi confirms a haplogroupi. 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 search for term
A grouping of those who share the same haplogroupi 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 search for term
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 SNPi mutationi is called a haplogroups.
HVR search for term
Hyper Variable Region. The sections of non-coding mitochondrial DNA that are used for genealogical DNA testing.
ISOGG search for term
International Society of Genetic Genealogyi, a free society founded in 2005 for the promotion and education of genetic genealogy.
JoGG search for term
The Journal of Genetic Genealogyi - An online journal published quarterly with articles and features pertaining to genetic genealogy and anthrogenealogy. http://www.jogg.info/
Junk DNA search for term
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 search for term
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 resultsi, and helping resolve conflicts when they occur.
lineage search for term
Persons whose DNA test resultsi show that they share a recent common ancestor since the advent of surnames (circa 1100 AD).
Marker search for term
A type of non-coding Y-chromosome DNA. The numbers designating your individual DNA segment numbers you receive with Y-chromosome DNA resultsi. Example: 393=13. This means at marker #393, your allelei value is 13.
Meiosis search for term
The stage in which sperm and egg cells are formed. It is during this process that the autosomal chromosomes recombine and mutations occur.
Mitochondria search for term
A specific organelle in the cell that helps it to produce energy.
Mitochondrial DNA search for term
Energy releasing organelles located in the cytoplasm of cells, which contain their own DNA. Mitochondrial DNAi is passed from mother to child, but only females continue to pass on their maternal mitochondria to their children.
Mitosearch search for term
A free public database sponsored by Family Tree DNA where mitochondrial DNA resultsi from any testing facility may be uploaded and compared. http://www.mitosearch.org/
Modal haplotype search for term
The most common result for each marker tested in a group of resultsi. See also: ancestral signature.
MRCA search for term
Acronym for Most Recent Common Ancestor.
mtDNA search for term
Acronym for mitochondrial DNA.
mutation search for term
A change in the DNA that occurs at random. In genetic genealogy, a mutationi is usually beneficial, as mutations on the y-chromosome are often used in distinguishing different ancestral lines.
Mutation rate search for term
The frequency with which random mutations occur.
Non-coding DNA search for term
Also referred to as "Junk DNAi", non-coding DNA has no known biological function.
non-paternity event search for term
The genetic resultsi 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 search for term
DNA of chromosomes found in the nucleus of the cell.
Null search for term
A null is a value of zero on a marker. Nulls can occur due to missing genetic material on a marker, or a SNPi can sometimes cause a null result. Several YSTRi markers have been identified in certain families to have null resultsi: 439, 448
personal page search for term
Your page at FTDNAi where you can list your contact information, earliest known ancestors, join additional projects, and choose how and where to compare your resultsi.
Pherogram search for term
For STRs, a plot which shows the length of a fragment of DNA. This allows its allelei value to be measured.
Phylo-tree search for term
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 search for term
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 RAOi, Family Tree DNA clients need to click the tab on their "My FTDNAi" page.
recLOH search for term
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 allelei 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 search for term
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 search for term
A protein that recognizes a certain sequence of DNA and cuts the DNA at that site.
Restriction Fragment Length Polymorphism (RFLP) search for term
See single nucleotide polymorphism.
results search for term
A table from the testing company showing a listing of the markers that have been tested, with a number for each marker. These resultsi are posted at FTDNAi and on the Results Page of your surname DNA project.
Sex chromosome search for term
The X- or Y-chromosome. Normally males have one X and one Y and females have two Xs.
site search search for term
Allows you to search the entire website for a particular name or word.
SNP search for term
Single Nucleotide Polymorphism (pronounced "snip"); a SNP testi confirms your haplogroupi by determining if a SNPi has mutated from its ancestral state. A SNP is usually found on a different area of the Y-chromosome than where the YSTRi markers are.
SNP test search for term
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 search for term
Acronym for Short Tandem Repeat - See: YSTRi
Sub-clade search for term
Referring to a "branch" farther down the phylogenetic tree. Example: H3 -> '3' is a sub-clade of mitochondrial haplogroupi 'H'. R1b -> '1b' is a sub-clade of Y-chromosome haplogroup 'R'. Sub-clade '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."> '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." class="glossary-indicator active">i testing is also referred to as deep clade testing.
testing kit search for term
The swabs sent to you by FTDNAi to rub the inside of your cheek to obtain skin cells which will be tested for your DNA.
Time to the Most Recent Common Ancestor (TMRCA) search for term
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 search for term
The passage of genetic material from one generation to the next.
Unique Event Polymorphism (UEP) search for term
See single nucleotide polymorphism
X-chromosome search for term
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 search for term
A free public database sponsored by DNA Heritage where Y-chromosome DNA resultsi from any testing facility may be uploaded and compared.
Y-DNA phylogenetic tree search for term
A graphic representation of the Y-DNA haplogroups according to the YCC classification. Haplogroup names and major clades are labeled and mutationi names are given along the branches of the trees.
Y-Search search for term
A free database sponsored by Family Tree DNA where Y-chromosome DNA resultsi from any testing facility may be uploaded and compared.
YSTR search for term
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'.