A DNA identity profile is an innate, lifelong and unchangeable identifier. It makes an animal unambiguously recognisable and at the same time forms the basis for further analyses. This article explains what such an "identity" DNA profile consists of, which key figures determine its power, and how a stated parentage can be assessed with it.
The idea of unambiguously identifying an individual from its unique genome is about four decades old. The technology behind it has changed fundamentally in that time – but the basic approach has stayed the same: at selected, readily measurable positions, the composition of the DNA is examined. Taken together, an individual pattern emerges (the "identity" DNA profile) that reliably sets an animal apart from all others.
The British geneticist Sir Alec Jeffreys discovers DNA fingerprinting. He uses highly variable repeat regions (so-called minisatellites) whose pattern differs from one individual to the next. In 1985 the method is first used in a legal case to clarify a relationship.
Next come the Short Tandem Repeats (STR), also called microsatellites: each STR marker has a large number of variants (alleles), each of which is inherited. The sum of the alleles of all STR markers in a defined set forms the "identity" DNA profile. As recommendations of the ISAG, STR markers provided the international reference for decades.
Generatio actively contributed to developing the ISAG recommendations and built the largest STR-marker-based DNA programme for the SV.
Today, DNA identities based on SNP profiles are becoming established. An SNP (Single Nucleotide Polymorphism) is the smallest unit of variation; the difference in a single DNA building block gives rise to two different alleles. Many such positions together likewise yield a unique, particularly stable and easily standardised profile.
Generatio's SNP profiles are based on the particularly robust SNP array technology.
A DNA profile is only as meaningful as its ability to reliably tell two randomly chosen animals apart. This discriminatory power can be described with a few statistical measures. They show how unlikely it is that two different individuals carry the same profile.
The random match probability states how likely it is that a randomly selected, unrelated animal carries the same profile. Across many markers the individual probabilities multiply – the overall result quickly reaches the order of one in many billions. The smaller the RMP, the more unambiguous the profile.
The power of discrimination is essentially the counterpart to the RMP: it describes how reliably any two individuals are told apart. In parentage testing the power of exclusion also matters – the probability of reliably excluding a false parentage from the markers.
A marker is only useful if its variants occur frequently and in a balanced way in the population. A high minor allele frequency and a high degree of heterozygosity mean that many animals carry different genotypes at that position – and that is exactly what creates discriminatory power.
The PIC value summarises how much "distinguishing information" a single marker provides. It combines the number of alleles and their frequency distribution into one measure. A profile is therefore assembled not from as many markers as possible, but from the most informative and robust ones.
For DNA profiles to be comparable worldwide, a common standard is needed. For animal genetics, the ISAG (International Society for Animal Genetics) defines the marker sets that are used. It specifies which markers must be determined and which serve as additional markers – producing a profile that fits together across laboratory and national borders.
The ISAG recommends a fixed core panel of mandatory markers, supplemented by additional back-up markers. For the established STR standard these were, for example, 17 microsatellites (12 mandatory, 5 optional); the SNP panels follow the same principle with a shared core and defined additional markers.
A uniform core set ensures that a profile from laboratory A can be matched against a profile from laboratory B. Especially for international breeding, re-imports and data exchange between associations, this standardisation is decisive.
Note: the specific panels are maintained on an ongoing basis by the ISAG working groups and may evolve in detail. The version currently valid for a given species should be requested from the performing body or the responsible breeding association.
For each marker, an offspring inherits one allele from the sire and one from the dam. A parentage assessment checks whether the offspring's profile can be explained by the profiles of the stated parents. If a marker clearly contradicts the stated parentage, that points to an exclusion. If all markers fit together, the analysis calculates how strongly the data support the stated relationship – via the likelihood ratio (LR).
When sire and dam are available, it can be determined unambiguously for each marker which of the offspring's alleles may come from which parent. This gives the highest informative value: the LR reaches very large numbers, and an error in the stated parentage is detected reliably.
If only one parent is known, the contribution of the missing parent must be estimated from the allele frequencies of the population. The calculation remains valid, but the LR comes out lower because part of the information is missing. In borderline cases more markers may therefore be needed to reach the required confidence level.
Since 2001, Generatio has created the STR marker profiles for the SV (German Shepherd Dog Association), thereby realising the world's furthest-reaching and largest DNA-secured studbook. This experience goes far beyond dogs: for numerous other species too, we create identity and parentage profiles with many years of routine.
Partner to breed associations for over 20 years – from a single litter to an association-wide, DNA-secured studbook. Reliable parentage control and unambiguous identity for every breed.
To the shop item →Specialised expertise for camelids: identity assurance and proof of parentage for breeding, trade and registration – including demanding cases.
To the shop item →Parentage control and identity profiles to a recognised standard – the reliable basis for breeding associations, registration and international data exchange.
To the shop item →For New World camelids: unambiguous DNA profiles to secure parentage and to build continuous, traceable breeding documentation.
To the shop item →The most important questions about DNA identity profiles, their limits and their use in parentage assessments – answered briefly and clearly.
The simplest way is to have a DNA identity profile created early for every breeding animal – ideally before its first use for breeding – and to keep it permanently. Because the profile stays unchanged for life, it becomes a fixed reference. Then, for every litter, have the parentage of the offspring verified against the stored parent profiles. This builds a seamless, DNA-secured chain generation after generation.
Two things safeguard continuity: consistently use the same marker format (e.g. SNP or STR) so that all profiles remain comparable, and have the profiles archived in one place. Generatio retains the profiles it creates, so they can be drawn on again at any time for later litters, sales or subsequent breeding – even years later.
No. The markers of an identity profile are deliberately selected to have a high minor allele frequency and to distinguish individuals as well as possible. They are therefore intentionally "made variable" and are not representative of the whole genome. Inferring genome-wide genetic diversity (such as the degree of inbreeding or the diversity of a population) from these few, specially chosen positions is therefore not valid – that requires other, genome-wide analyses.
No. For a parentage assessment, the profiles of everyone involved must be in the same format. STR markers (repeat lengths) and SNP markers (single-base variants) measure different things at different positions and cannot be compared directly against each other. If only an STR profile is available for one parent and an SNP profile for the offspring, the missing profile must be re-determined in the matching format (or – where established and permitted – converted by imputation).
No. The markers used usually lie in neutral, non-coding regions of the genome and were selected solely for their discriminatory power, not for any link to traits. An identity profile answers the question "Which animal is this?" – it is not a genetic test for diseases, colours or breeding values. Such questions require their own specific analyses.
Not necessarily. A single inconsistency can be due to a rare mutation or a technical effect. In practice, a parentage is only considered excluded when several markers contradict it independently. A single "mismatch" is assessed, documented and – where sensible – checked by re-testing before any conclusion is drawn.
No. The DNA profile is innate and remains unchanged for life – regardless of the type of sample (e.g. hair, blood or mucosa) and the age of the animal. It therefore never needs renewing and serves as a permanent, tamper-proof reference, for example for re-identification or as the basis for later parentage assessments.
These answers are for general information. For assessing an individual case, the rules currently in force at the performing body and the responsible breeding association are decisive.