A new set of 20 Multi-InDel markers for forensic application

Area of Science:

• Forensic Genetics
• Molecular Biology
• Population Genetics

Background:

• Insertion/deletion (InDel) markers are valuable in forensic medicine due to compatibility with STR typing and lower mutation rates.
• Multi-InDel markers, comprising multiple linked InDels, offer enhanced application potential but face typing challenges with capillary electrophoresis (CE).
• Existing Multi-InDel typing methods often lack the length discrepancy needed for direct CE analysis.

Purpose of the Study:

• To develop and evaluate a CE-based typing system for 20 Multi-InDel markers (41 InDels).
• To assess the forensic application potential of this Multi-InDel typing system in a Chinese Han population.
• To determine the genetic parameters, including allele frequencies and forensic efficiency, of the developed system.

Main Methods:

• A multiplex system was designed to genotype 20 Multi-InDel markers, encompassing 41 individual InDel loci.
• The system was applied to genotype 200 unrelated Chinese Han individuals and five mother-child-father trios.
• Capillary electrophoresis (CE) was utilized for deducing Multi-InDel genotypes based on length discrepancies.

Main Results:

• The typing system successfully identified 70 specific alleles across the 20 Multi-InDel loci.
• High levels of polymorphism were observed, with 19 loci exhibiting more than three alleles and one locus showing seven alleles.
• The combined probability of exclusion reached 0.992, and the combined power of discrimination was 0.99999999993.

Conclusions:

• The developed CE-based Multi-InDel typing system is effective for individual identification and paternity testing.
• Multi-InDel markers represent a promising genetic tool for forensic applications, offering high polymorphism and low mutation rates.
• This research validates the utility of Multi-InDels as a valuable addition to forensic genetic analysis.