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DNA dictionary

Understand the terms you may see in a raw DNA file or an existing report. Examples are illustrative; they do not interpret an individual’s DNA.

18 terms found

Raw DNA file

Meaning
A text or table export listing selected genetic markers and the calls recorded at those positions.
Example
A row might show an rsID, chromosome, position and genotype.
Keep in mind
It is usually a panel of tested markers, not a complete genome sequence.

Related terms

Check a raw DNA file

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rsID

Meaning
A reference SNP identifier used by dbSNP to collect records about a reported DNA variant.
Example
A file may label a marker as rs123456.
Keep in mind
An identifier is a pointer to database records; it does not by itself describe health impact or ancestry.

Related terms

VariantSNPLook up an rsID

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Variant

Meaning
A difference in a DNA sequence compared with another sequence or a reference.
Example
At one position, a sequence may have C where another has T.
Keep in mind
“Variant” describes a difference; it does not say whether it matters for a trait or condition.

Related terms

SNPAlleleGenotype

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SNP

Meaning
A DNA variant at one nucleotide position. The letters stand for single nucleotide polymorphism.
Example
At one site, some records may show C and others T.
Keep in mind
A SNP can be common and harmless; the label alone does not establish an effect.

Related terms

VariantAllelersID

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Allele

Meaning
One version of a DNA sequence at a particular location.
Example
At a two-copy site, the alleles might be A and G.
Keep in mind
Some sites have more than two known alleles, and not every test measures every version.

Related terms

VariantGenotypeSNP

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Genotype

Meaning
The allele or combination of alleles recorded at a genetic location.
Example
A diploid SNP result may be written AA, AG or GG.
Keep in mind
A genotype call reports what the test read; it is not a diagnosis or a complete account of biology.

Related terms

AlleleNo-call

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No-call

Meaning
A tested position where the assay did not produce a reliable genotype result.
Example
A provider file may use “--” or “0” for an unreadable call.
Keep in mind
It means unknown at that position, not that a variant is absent or negative.

Related terms

GenotypeRaw DNA file

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Genome build

Meaning
A versioned reference genome assembly used to describe chromosome coordinates.
Example
The same variant can have different position numbers in GRCh37 and GRCh38.
Keep in mind
Coordinates need their assembly to be interpretable; converting a file format does not automatically lift coordinates between builds.

Related terms

rsIDVariantRaw DNA file

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Shared DNA

Meaning
DNA segments that two people have inherited from a common ancestor, often described as identical by descent (IBD).
Example
Two people may share several matching segments across autosomes.
Keep in mind
A single shared SNP is not evidence of a family relationship; segment pattern and context matter.

Related terms

Autosomal DNACentimorgan (cM)DNA match

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Centimorgan (cM)

Meaning
A genetic-distance unit based on the chance that recombination separates two markers.
Example
A shared-segment report may total the segments in centimorgans.
Keep in mind
It is not a fixed number of DNA letters, and shared cM alone does not identify a precise relationship.

Related terms

Shared DNADNA match

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DNA match

Meaning
A person whose tested DNA shares detectable segments with another person in a comparison database.
Example
A service may list a match and the amount of shared DNA.
Keep in mind
A match is a comparison result, not a verified identity or a certain relationship; DNA Info Lab does not match relatives.

Related terms

Shared DNACentimorgan (cM)Autosomal DNA

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Mitochondrial DNA (mtDNA)

Meaning
A small amount of DNA found in mitochondria, separate from the DNA in the cell nucleus.
Example
A test may read selected mtDNA positions.
Keep in mind
A typical autosomal raw file may not include mtDNA results.

Related terms

Maternal lineHaplogroup

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Maternal line

Meaning
One direct line of descent through mothers: a person, their mother, their mother’s mother, and so on.
Example
Mitochondrial DNA can trace clues along this direct line.
Keep in mind
It represents one branch among many ancestors, not a person’s whole maternal ancestry or family tree.

Related terms

Mitochondrial DNA (mtDNA)Haplogroup

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Genetic ancestry

Meaning
Information about inherited genetic relationships and, through comparison, clues about where some ancestors may have lived.
Example
A study may compare DNA patterns with reference samples from different regions.
Keep in mind
Genetic ancestry is not the same as cultural identity, ethnicity or a complete family history.

Related terms

Autosomal DNAAncestry estimateReference population

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Ancestry estimate

Meaning
A statistical result comparing genetic patterns with chosen reference data and a particular method.
Example
One report might assign a broad region where another uses different labels or proportions.
Keep in mind
It is an estimate shaped by samples and methods, not a precise map of identity or every ancestor.

Related terms

Genetic ancestryReference populationAutosomal DNA

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Reference population

Meaning
A comparison group with genetic data used as a reference when estimating ancestry.
Example
A method may compare someone’s markers with samples labelled by geographic region.
Keep in mind
Groups may be unevenly represented, and estimates can change when data or methods change.

Related terms

Genetic ancestryAncestry estimate

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