Case report on multilocus gene deletion and gene conversion at Y-STR loci.

Y-chromosomal short tandem repeats (Y-STRs) are pivotal tools in forensic science, such as paternity testing, male lineage tracing, and genealogical investigations. However, traditional models, such as the stepwise mutation model (SMM) fail to address more complex mutation mechanisms, such as gene deletion and gene conversion. These limitations hinderthe accuracy of lineage analyses, particularly for multi-copy loci. This study analyzed two types of Y-STR mutation abnormalities through five detailedcases, using STR typing andnext-generation sequencing (NGS) technology. Biological samples from 5 father-son and father-cousin pairs were genotyped withthe Yfiler™ Platinum Kit and the Microreader™ RM-Y ID kit.The STR typing was conducted using the next-generation sequencing STRTyper Y68 Kit. A gene conversion mutation was observed at the multicopy locus DYS385ab in Case 1.The deletion of multicopy loci (DYS527ab, DYS387ab, DYF404S1, DYS464, DYS399S1, DYS626, and DYS448) within the the five male pedigree samples (father-son or uncle-nephew) pairs c region was observed in cases 2-5. This finding highlights the limitations of single-step mutation models (SMM) in analyzing multi-copy Y-STR loci and underscores the necessity of incorporating non-stepwise mutation mechanisms into forensic methodologies.This study advances understanding of Y-STR mutation dynamics, providing significant implications for forensic science and human genetics.