Applicability of imprinted DIP-SNP markers in DNA mixture analysis: a pilot study.

Area of Science:

• Forensic Genetics
• Molecular Biology

Background:

• Deletion/insertion polymorphism-single nucleotide polymorphism (DIP-SNP) markers are used in forensic DNA mixture analysis.
• Current DIP-SNP genotyping methods, like capillary electrophoresis (CE), often require multiple reactions and are challenging for complex mixtures.

Purpose of the Study:

• To develop a multiplex polymerase chain reaction (PCR) assay for imprinted DIP-SNP markers using the amplification refractory mutation system (ARMS) principle.
• To evaluate the effectiveness of parentally imprinted allele (PIA) typing for analyzing imbalanced DNA mixtures.

Main Methods:

• Selected four candidate imprinted DIP-SNP markers for multiplex PCR.
• Applied the amplification refractory mutation system (ARMS) for a one-tube reaction.
• Utilized parentally imprinted allele (PIA) typing to detect parental alleles and an improved RMNE method for mixture analysis.

Main Results:

• Confirmed maternal imprinting for rs35918685-rs185148 and rs11667883-rs76183558, with consistent imprinting across saliva, vaginal fluid, and menstrual blood.
• Successfully detected a minor DNA contributor in a 1:20 ratio in a two-person DNA mixture, demonstrating high analytical sensitivity.
• PIA-based interpretation showed improved efficiency in narrowing down potential contributors compared to conventional genotyping.

Conclusions:

• Imprinted DIP-SNP markers possess significant forensic potential, especially for imbalanced DNA mixtures.
• The developed multiplex PCR assay and PIA typing offer a sensitive and efficient approach for forensic DNA analysis.