Applying massively parallel sequencing to paternity testing on the Ion Torrent Personal Genome Machine

Area of Science:

• Forensic genetics
• Molecular biology
• Human genetics

Background:

• Massively parallel sequencing (MPS) is increasingly used in forensic genetics.
• Capillary electrophoresis (CE) typing can present mismatched loci in forensic casework.
• Paternity testing relies on accurate Short Tandem Repeat (STR) analysis.

Purpose of the Study:

• Evaluate the performance of MPS in paternity testing for cases with mismatched STR loci identified by CE.
• Determine the certainty of paternity and analyze mutations using MPS.
• Identify novel STR alleles and assess the utility of MPS in forensic genetics.

Main Methods:

• Analysis of 15 samples from seven paternity testing cases with one mismatched locus by CE.
• Application of Massively Parallel Sequencing (MPS) on an Ion Torrent Personal Genome Machine.
• Calculation of Combined Paternity Index (CPI) and relative chance of paternity according to international and Chinese standards.

Main Results:

• MPS confirmed paternity with high certainty (CPI > 10,000), classifying mismatched alleles as mutations.
• The origins of mutations were inferred by detecting allele sequence structures.
• Nine STRs showed an increased number of unique alleles, and three novel alleles were detected in D2S441, D21S11, and FGA.

Conclusions:

• MPS is a valuable tool for forensic genetics, offering high certainty in paternity testing.
• MPS can resolve discrepancies observed with traditional methods like CE.
• The detection of novel alleles and mutation analysis by MPS contributes to forensic genetics research.