Population-specific FST values for forensic STR markers: A worldwide survey

Area of Science:

• Forensic Science
• Population Genetics
• Genetics

Background:

• DNA profile matching in forensics uses population genetic models to estimate the probability of chance matches.
• Accurate allele frequencies are crucial but often unavailable for specific target populations, necessitating use of broader databases.

Purpose of the Study:

• To quantify population structure (FST) affecting DNA profile matching probabilities.
• To estimate FST from existing forensic literature data.
• To evaluate the conservatism of current forensic theta values.

Main Methods:

• Extracted allelic matching proportion data from 250 forensic literature papers.
• Analyzed data representing STR profiles from nearly 500,000 individuals across 446 populations.
• Estimated FST values based on within- and between-population matching proportions.

Main Results:

• FST values were estimated from a large-scale analysis of published forensic genetic data.
• The study demonstrated that FST can be reliably estimated from sample allelic matching proportions.
• Estimated FST suggests current forensic theta values may not be as conservative as commonly assumed.

Conclusions:

• Population structure (FST) significantly impacts DNA profile match interpretation.
• Estimates of FST derived from literature data provide insights into population variation.
• The conservatism of current forensic theta values requires re-evaluation based on empirical FST estimates.