Glossary of Terms
Autosomal DNA (atDNA): 22 pairs of non-sex chromosomes found in the nucleus of a cell.
Autosome: One of the numbered non-sex chromosomes.
Cell: The basic unit of life that contains DNA.
Centimorgans: A unit of measurement used to imply distance along a chromosome.
Chromosome: A DNA molecule found in the nucleus of living cells.
Chromosome Browser: A visual representation of shared DNA between two test takers.
DNA (deoxyribonucleic acid): A double-stranded molecule containing genetic information.
DNA Match: Two test takers that share DNA.
DNA Segments: A position on a chromosome where two test takers share DNA.
Ethnicity estimate: Inferred ancestral origins based on comparing an individual’s DNA to that of a genetic reference population.
Endogamy: The custom of marrying only within the limits of a local community, clan or tribe.
FTDNA Projects/Surname groups: A free research group of test takers at FamilyTreeDNA that share a common ancestry.
Genetic genealogy: The practice and study of using DNA in genealogical research.
Genome: An organism’s complete set of genetic instructions. Each genome contains all of the information needed to build that organism and allow it to grow and develop.
Half-identical region (HIR): A region of two paired chromosomes where at least one of the two alleles from one person's pair of chromosomes matches at least one of the two alleles from a different person's pair of chromosomes throughout the entire region.
Haplogroup: Group of people that share genetic mutations and a common ancestor
Haplotype: A test taker’s specific marker results.
Marker: A specific commonly test region of DNA.
Matrilineal: The direct maternal line.
Mitochondrial DNA (mtDNA): A type of DNA found with many copies in almost all cells. It is passed down from the mother to all of her children, but only her daughters can pass it to the next generation. However, a man or women can test and determine their mother’s results, which defines their maternal line
Most recent common ancestor (MRCA): The common ancestor closest to two or more DNA.
Matches: People that share DNA.
Mutation: A variation in DNA that occurs over generations.
Nucleotide: One of four building blocks of DNA (adenine, cytosine, guanine, and thymine)
Nucleus: The cell’s control center.
Patrilineal: The direct paternal line.
Phasing: The task or process of assigning alleles (the As, Cs, Ts and Gs) to the paternal and maternal chromosomes. The term is usually applied to types of DNA that recombine, such as autosomal DNA or the X-chromosome.
Recombination: The mixing of autosomal DNA with the creation of a child.
Reference groups: People with whom a test taker’s DNA is compared that represent specific ethnic or geographic groups.
Shared cM Project: A reference work produced by Blaine T. Bettinger for evaluating relationships based on the amount of shared DNA.
SNP “snip” (Single nucleotide polymorphism): A variation of a single DNA base pair. They represent nucleotide differences and are used to help establish relationships between matches
STR (Short Tandem Repeats): A repeated DNA sequence. Used to help establish relationships between matches
Terminal SNP: The snip that most closely defines the test taker
X-DNA: A sex chromosome in the cell nucleus that males inherit only from their mothers and females inherit from both parents.
Y-DNA: A sex chromosome in the cell nucleus that males inherit only from their fathers, which defines their paternal line.
