New reference allelic ladders to improve allelic designation in a multiplex STR system

Area of Science:

• Forensic Science
• Genetics
• Molecular Biology

Background:

• Multiplex DNA profiling systems rely on accurate allelic ladders for locus identification.
• Existing allelic ladders may not encompass the full spectrum of known alleles, particularly rare ones.
• Standardization in forensic genetics is crucial for reliable DNA analysis.

Purpose of the Study:

• To report the composition of a novel reference allelic ladder mixture.
• To enhance the capabilities of a specific multiplex DNA profiling system.
• To improve the identification of rare alleles in forensic casework.

Main Methods:

• Development of a multiplex allelic ladder mixture for six short tandem repeat (STR) loci and an amelogenin sex test.
• Sequence analysis of individual ladder alleles.
• Allelic designations aligned with International Society of Forensic Haemogenetics (ISFH) recommendations.

Main Results:

• A new reference allelic ladder mixture was successfully created.
• Rare alleles, expanding the previously reported range, were identified and incorporated.
• The inclusion of rare alleles significantly improved the system's ability to detect new alleles in unknown samples.

Conclusions:

• The developed allelic ladder mixture is a valuable tool for multiplex DNA profiling.
• The enhanced ladder improves the discriminatory power of DNA analysis by accommodating rare alleles.
• This advancement contributes to more comprehensive and accurate forensic DNA identification.