Population and forensic genetic data of 27 Y-STR and 12 X-STR loci in four British Isles populations

This study presents population data for 27 Y-chromosomal STR (Y-STR) loci and 12 X-chromosomal STR (X-STR) loci from 888 unrelated males representing four populations of the British Isles (English, Irish, Scottish, and Welsh). Genotyping was performed using the Yfiler Plus and Investigator Argus X-12 QS kits under ISFG-aligned quality control procedures. All four populations exhibited 100 % haplotype diversity for both marker systems, confirming strong discriminatory capacity. Several rare allelic variants were identified, including deletions, insertions, and a tri-allelic pattern among Y-STRs, as well as insertion events at X-STR loci. Linkage disequilibrium (LD) analysis revealed patterns consistent with the physical arrangement of X-STR loci, with marginally significant LD detected within several linkage groups in the English and Irish populations. Based on these results, haplotype-based analyses were conducted using all 886 valid male profiles across the four linkage groups, showing that LG1 and LG4 exhibited the highest discriminatory capacities. Phylogenetic and multidimensional scaling analyses incorporating global reference datasets revealed clear and interpretable patterns of population structure. Y-STR data positioned the British Isles populations within a north-western European paternal cluster, with Irish and Welsh forming a distinct Celtic subgroup. X-STR results showed a close maternal-line relationship between English and German populations consistent with Anglo-Saxon migrations, and a separate Celtic cluster comprising Irish and Welsh, with the Scottish population showing intermediate affinity. Overall, this study provides a robust and forensically relevant dataset reflecting both paternal and maternal genetic diversity across the British Isles, improving the accuracy of forensic identification and kinship analysis. • Genetic data from 888 males across four British Isles populations. • High haplotype diversity for 27 Y-STR and 12 X-STR loci. • Novel allelic variants identified, including tri-allelic Y-STR patterns. • Data supports forensic casework and kinship analysis applications. • Quality control aligned with ISFG recommendations.