Glossary
Dog genetics, in plain words
A dog DNA report comes with its own vocabulary. This glossary explains the terms you're most likely to meet, with examples from real dog genetics. Terms with a full guide link to it.
A to Z
- Allele
- One version of a gene. A dog has two alleles of most genes, one from each parent, and they can be the same or different.
- Ancestry estimate
- An estimate of how much of a dog's DNA traces back to each breed, shown as percentages. It's a probability-based estimate, not a pedigree.
- Autosome
- Any chromosome other than the X and Y sex chromosomes. Dogs have 38 pairs of autosomes.
- Base pair
- One rung of the DNA ladder: two matching chemical letters (A with T, or C with G). Genomes are measured in billions of base pairs.
- Breed clade
- A group of breeds that share ancestry. A 2017 study sorted 150 breeds into 23 clades of related breeds.
- Carrier
- A dog with one copy of a recessive variant. It doesn't show the trait, but it can pass the variant on, and two carriers can have puppies that show it.
- Chromosome
- A long, tightly packed strand of DNA. Dogs have 78 chromosomes in each body cell: 38 pairs plus two sex chromosomes.
- COI (coefficient of inbreeding)
- An estimate of how much of a dog's genome carries matching copies because they trace back to shared ancestors.
- Confidence
- In a DNA report, how strongly the sample supports a result. A low-confidence result is tentative and may not match the dog in front of you.
- Dilute
- A coat colour lightened by two copies of a recessive variant in the MLPH gene, for example black lightened to grey.
- DNA
- The molecule that carries genetic instructions, written in four chemical letters. Inherited DNA doesn't change as a dog ages.
- Dominant
- A version of a gene that shows its effect with just one copy. The furnishings variant behind a doodle's beard is dominant.
- Double coat
- A coat with a soft, dense undercoat beneath longer guard hairs. Double-coated dogs shed their undercoat heavily as the seasons change.
- Eumelanin
- The black or brown pigment in a dog's coat, nose and eyes.
- F1, F1B, F2
- Breeders' shorthand for doodle generations: a first cross (F1), a first cross bred back to a Poodle (F1B), and a cross of two F1s (F2).
- Furnishings
- The beard, moustache and eyebrows of wire-haired breeds and most doodles, caused by a dominant variant of the RSPO2 gene.
- Gene
- A stretch of DNA that carries the instructions for one product, usually a protein. Variants of a gene can change a trait.
- Genome
- All of an organism's DNA. A high-quality draft of the dog genome was published in 2005.
- Genotype
- The versions of a gene a dog carries, often written as two letters, such as FF for two furnishings copies.
- Genotype imputation
- Filling in genotypes at positions that weren't read directly, by comparing the DNA that was read with a reference panel of dogs.
- Heritability
- How much of the variation in a trait, across a group of animals, comes from genetic differences rather than environment.
- Heterozygous
- Carrying two different versions of a gene, one from each parent.
- Homozygous
- Carrying two copies of the same version of a gene.
- Improper coat
- A doodle without furnishings: a smooth face and a flatter coat, because it inherited no copies of the furnishings variant.
- Inbreeding
- Breeding between related dogs, which makes it more likely that a dog inherits matching copies of genes from a shared ancestor.
- Incomplete dominance
- When one copy of a variant has a partial effect and two copies a stronger one, like the curl gene: one copy usually wavy, two curly.
- Locus
- A position in the genome, often used to mean a gene and its versions. Coat colour genes are known by locus letters, such as E, K and A.
- Low-pass sequencing
- Reading a genome at low coverage, often around one read per position, and relying on imputation to fill in the gaps.
- Merle
- A coat pattern of diluted patches, caused by an insertion in the PMEL (SILV) gene.
- Phaeomelanin
- The red-to-yellow pigment in a dog's coat, from cream through gold to deep red.
- Phenotype
- A trait you can see or measure, such as a curly coat, a beard or blue eyes.
- Polygenic trait
- A trait shaped by many genes at once, each with a small effect, such as body size or behaviour.
- Recessive
- A version of a gene that only shows its effect when a dog has two copies, such as the long-coat variant of FGF5.
- Reference panel
- A collection of DNA from dogs of known breeds or populations that a test compares a sample with.
- SNP
- A single-nucleotide polymorphism: a spot in the genome where dogs differ by a single DNA letter. SNPs are the most common markers used to compare dogs' DNA.
- Tan points
- Tan markings on the face, chest and legs of a darker coat, from one version of the ASIP gene, as in Dobermans and phantom Poodles.
- Unresolved ancestry
- The part of a dog's DNA that a breed estimate couldn't confidently assign to a single breed, including small, uncertain contributions.
- Variant
- A difference in a DNA sequence compared with a reference. Variants are what make alleles different from each other.
All guides
What Is an Allele? Definition and Dog Examples
An allele is one version of a gene. Here's what that means, why a dog carries two alleles of most genes, how one gene can have many alleles across dogs, and examples from dog coats.
Read
Dominant vs Recessive Genes in Dogs, Explained Simply
Why one copy of the furnishings gene gives a doodle its beard but a long coat takes two copies: dominant and recessive genes in dogs, what a carrier is, the odds for each pairing, and the traits in between.
Read
Genotype Imputation, Simply Explained (With Dog DNA)
Genotype imputation fills in the DNA positions a test didn't read directly, by comparing what it did read with a reference panel of dogs. Here's how it works, what a 2022 dog study found about its error rate, and its limits.
Read
Genotype vs Phenotype: The Difference, With Dog Examples
Genotype is the set of gene versions a dog carries; phenotype is what you can see. Here's how the two connect, using dog coats as examples, and why a dog's DNA doesn't always match its looks.
Read
Heritability: What It Means for Dogs (and What It Doesn't)
Heritability measures how much of the variation in a trait, across a group of dogs, comes from genetic differences. Here's what it means, what two large dog behaviour studies found, and the most common ways it's misread.
Read
Heterozygous vs Homozygous, Explained With Dogs
Homozygous means two copies of the same gene version; heterozygous means two different ones. Here's what that looks like in dog coats, what it means for puppies, and how it connects to inbreeding.
Read
How Many Chromosomes Do Dogs Have? 78, Explained
Dogs have 78 chromosomes in each body cell: 38 pairs of autosomes plus two sex chromosomes. Here's what that means, how dogs compare with people, and how a puppy inherits half its chromosomes from each parent.
Read
What Is a Locus? Why Dog Coat Genes Have Letters
A locus is a fixed position in the genome, often used to mean a gene and its versions. Here's what the word means, why dog coat colour genes go by letters like E, K and A, and how loci connect to traits.
Read
Low-Pass Whole-Genome Sequencing, Explained
Low-pass whole-genome sequencing reads DNA from across the whole genome, but thinly, then fills the gaps by imputation. Here's how it works, what coverage means, how it compares with SNP chips, and its limits.
Read
Polygenic Traits: Why Most Dog Traits Involve Many Genes
A polygenic trait is shaped by many genes at once. Here's why body size and behaviour work that way in dogs, how they differ from single-gene traits like furnishings, and what that means for DNA predictions.
Read
What Is a Reference Panel in a Dog DNA Test?
A reference panel is the set of dogs of known breeds or populations that a DNA test compares your dog with. Here's how it's used for breed ancestry, imputation and diversity, why its make-up matters, and what to ask about it.
Read
What Is a SNP? Single-Nucleotide Polymorphisms in Dogs
A SNP is a spot in the genome where dogs differ by a single DNA letter. Here's what SNPs are, how they're written, how they helped researchers find the genes behind dog traits, and how DNA tests read them.
Read
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