Forensic DNA phenotyping in Southeast Asian populations: a scoping review

Abstract

Forensic DNA phenotyping (FDP) provides vital investigative leads by predicting externally visible characteristics (EVCs). However, a significant “genomic gap” exists as most FDP models are calibrated on European or East Asian datasets, limiting their reliability in the genetically diverse Southeast Asian (SEA) region. This scoping review, following PRISMA-ScR guidelines, systematically mapped genetic markers for pigmentation and craniofacial morphology across SEA populations. We synthesized data from 25 eligible studies (2020–2025) including genome-wide association studies and whole-genome sequencing. Results reveal pronounced intra-regional genetic heterogeneity, particularly in SLC24A5 and OCA2 loci, with allele frequencies (e.g., rs1426654) showing sharp stratification between Western and Eastern Indonesian groups. Furthermore, novel associations for skin texture, ADGRL2 for cheek color and LINGO2 for pore size, were identified in Thai and Indonesian cohorts yet remain absent from standard forensic panels. Evaluation of current FDP tools (e.g., ForenSeq, HIrisPlex-S) demonstrates reduced resolution for differentiating closely related SEA sub-populations. These findings highlight the limitations of uniform ‘Asian’ reference panels and highlight the risk of predictive bias. We conclude that region-specific genomic databases are essential to improve the accuracy and equity of DNA-based facial prediction in SEA. • A significant genomic gap exists for Southeast Asian populations in forensic DNA phenotyping, as most predictive models rely heavily on European or East Asian datasets. • Southeast Asian populations exhibit pronounced intra-regional genetic heterogeneity, evidenced by sharp stratification in key pigmentation loci such as SLC24A5 and OCA2. • Novel genetic markers for skin texture, including ADGRL2 for cheek color and LINGO2 for pore size, have been identified in Southeast Asian cohorts but are not yet integrated into standard forensic panels. • The application of existing commercial forensic DNA phenotyping tools yield reduced resolution and accuracy when attempting to differentiate closely related sub-populations within the Southeast Asian region. • The establishment of region-specific genomic reference databases is crucial to mitigate predictive bias and enhance the reliability of forensic facial predictions in Southeast Asia.