Externally Visible Characteristic (EVC)
Definition
An observable physical trait (eye colour, hair colour, skin tone, height, facial morphology) whose variation in the population is partly genetically determined and can be predicted from SNP genotypes. EVC predictions are investigative intelligence, not identification evidence.
- Examples
- Eye colour, hair colour, skin tone, height, facial morphology
- Genetic basis
- Predicted from SNP genotypes
- Evidentiary status
- Investigative intelligence, not identification evidence
- Field
- DNA phenotyping / forensic genetics
Common questions
Why is an EVC prediction called investigative intelligence rather than identification evidence?+
The prediction gives a probability over a trait, such as likely eye colour, that can narrow a suspect pool or generate leads, but does not uniquely identify an individual the way a full STR profile match does, so it supports investigation rather than courtroom identification.
How accurate are current EVC predictions across different traits?+
Accuracy varies by trait. Eye and hair colour predictions from panels like IrisPlex and HIrisPlex tend to be relatively strong for categorical outcomes, while traits like precise facial morphology or height are more polygenic and predicted with substantially less precision.
Related terms
- Ancestry-Informative Marker (AIM)
- A SNP with an allele-frequency difference (FST) above 0.4 or 0.5 between continental population groups. A panel of 100-200 AIMs provides probabilistic...
- FORENSeq DNA Signature Prep
- Commercial MPS kit from Verogen that types STRs, Y-STRs, X-STRs, identity SNPs, AIMs, and EVC SNPs in a single library preparation and...
- HIrisPlex-S
- A 41-SNP externally visible characteristics (EVC) panel for simultaneous prediction of eye, hair, and skin colour, developed at Erasmus MC Rotterdam by...
- Parabon Snapshot
- A commercial DNA phenotyping service (Parabon NanoLabs, Virginia, US) that genotypes thousands of SNPs from a crime-scene sample and uses machine learning...
- SNPforID Consortium
- European-funded research consortium that published the foundational 52-SNP identity panel for forensic use in 2004-2006. The 52-plex is validated for maximum discriminating...