DNA database

A DNA database or DNA databank is a database of DNA profiles which can be used in the analysis of genetic diseases, genetic fingerprinting for criminology, or genetic genealogy. DNA databases may be public or private, the largest ones being national DNA databases.

DNA databases are often employed in forensic investigations. When a match is made from a national DNA database to link a crime scene to a person whose DNA profile is stored on a database, that link is often referred to as a cold hit. A cold hit is of particular value in linking a specific person to a crime scene, but is of less evidential value than a DNA match made without the use of a DNA database. Research shows that DNA databases of criminal offenders reduce crime rates.

Whether larger databases actually weaken match evidence has been debated. Stockmarr argued that searching a database increases the chance of coincidental matches, while Balding maintained that the evidence stays just as strong regardless of how the search was done. Recent analysis suggests both were partly right: traditional DNA profiling operates in a regime where false matches are so rare that database size barely matters, but threshold-based screening systems—which flag individuals matching some number of attributes rather than requiring an exact match—operate in a different regime where false alerts become statistically inevitable as populations grow.