Consistency of Familial DNA Search Results in Southeast Asian Populations

DNA databases are widely used in forensic science to identify unknown offenders. When no exact match is found, familial DNA searches can help by identifying first-degree relatives using likelihood ratios. If multiple subpopulations are relevant, likelihood ratios can be computed separately based on allele frequency estimates. Various strategies exist to combine these ratios, such as averaging allele frequencies or taking the average, maximum, or minimum likelihood ratio. While some comparisons have been made in populations like those in the U.S., their effectiveness in other regions remains unclear. This study evaluates likelihood ratio-based strategies in Southeast Asian populations, specifically Thailand, Malaysia, and Singapore. Our findings align with previous research, showing that statistical power varies across strategies. Among Thai subpopulations, the minimum likelihood ratio strategy is preferred, as it maintains high power while minimizing differences between subpopulations.