The implementation of large-scale forensic DNA databases under legal frameworks, such as Law 8611 in Mendoza (Argentina), provides an unprecedented opportunity to study Y-chromosomal variation. This study characterizes the genetic landscape of the Mendoza population using a massive dataset, focusing on haplotype diversity and the documentation of rare genetic events—such as microvariants and structural mutations—that can impact forensic interpretation.

A total of 22,227 saliva samples, collected using Bode Buccal Collector™, were processed at the Provincial DNA Database using the YFiler™ Plus PCR Amplification Kit (27 loci). Quality control is ensured through annual participation in the ISFG Proficiency Testing (GHEP-ISFG). Data processing, including the identification of unique haplotypes and frequency calculations, was performed using Python-based bioinformatic tools.

From the 22,227 profiles analyzed, 15,071 unique haplotypes were identified. The calculated Haplotype Diversity (HD) was 0.999915, indicating an exceptionally high power of discrimination for the Mendoza population. 

In addition to the frequency data, several genetic particularities were documented:

• Microvariants and Atypical Alleles: Numerous decimal alleles were identified, particularly in high-mutation loci.
• Structural Variations: A significant number of duplications and deletions (null alleles) were recorded. While anchor site mutations were not confirmed by secondary kits, they were documented as null alleles for forensic reporting purposes.
• Large deletions: Four haplotypes were identified with large deletions ranging from the loss of 5 to 16 STRs out of the 27 loci analyzed.

This study presents one of the most extensive Y-STR datasets in South America. The high HD value and the significant number of unique haplotypes underscore the robustness of the Mendoza Provincial Registry. Furthermore, the identification of frequent regional microvariants and structural anomalies highlights the vital importance of local reference databases to ensure accuracy in forensic casework and judicial certainty.

Authors

• Miguel Marino (Registro Provincial de Huellas Genéticas Digitalizadas, Mendoza Attorney General’s Office, Argentina)
• Dante Corradi (Registro Provincial de Huellas Genéticas Digitalizadas, Mendoza Attorney General’s Office, Argentina)
• Laura Locarno (Registro Provincial de Huellas Genéticas Digitalizadas, Mendoza Attorney General’s Office, Argentina)