DNAfingerprinting

DNA fingerprinting, also known as DNA profiling, is a laboratory method for identifying individuals based on characteristic patterns in their DNA. The approach targets regions of the genome that vary greatly among people, producing a DNA profile that can be compared with other profiles to determine a match or relatedness. The method is highly discriminating because most individuals have distinguishable patterns across multiple loci.

The development: In the 1980s, Sir Alec Jeffreys and colleagues introduced techniques based on restriction fragment length polymorphism (RFLP) analysis of variable number tandem repeats (VNTRs). With the advent of polymerase chain reaction (PCR), short tandem repeats (STRs) became the standard, enabling analysis from much smaller or degraded samples. Modern systems often rely on autosomal STRs and, in some cases, Y-STRs or mtDNA, with open national or international databases that store profiles.

Applications include criminal investigations, identification of disaster victims, paternity and relation testing, immigration cases, and wildlife forensics.

Limitations: a DNA profile does not reveal physical traits or health information. Identical twins share the same DNA profile at the loci tested. Mixed samples and degraded DNA can complicate interpretation; results rely on statistical assessment, including random match probability and likelihood ratios, and require proper laboratory controls and chain-of-custody.

Ethics and governance: use of DNA databases raises privacy concerns and consent issues; retention periods and access controls vary by jurisdiction. Legal admissibility generally requires validated methods, proper sampling, and transparent reporting.