Application of Probabilistic Genotyping Software to Paternity Cases Involving Low-Template DNA

Area of Science:

• Forensic Science
• Genetics
• Molecular Biology

Background:

• Interpreting short tandem repeat (STR) profiles from low-template DNA (LT-DNA) is challenging due to stochastic effects.
• Probabilistic genotyping software (PGS) is primarily used for direct comparisons, with limited application in kinship testing for LT-DNA.

Purpose of the Study:

• To evaluate the performance of two PGS (EuroForMix and EFMrep) in kinship testing with LT-DNA samples.
• To compare PGS performance against standard paternity testing software (Familias) in paternity cases.

Main Methods:

• Compared EuroForMix (EFM) and EFMrep with Familias in 33 paternity cases using LT-DNA samples.
• Assessed performance on 'mildly' (MD) and 'highly' (HD) degraded samples, including formalin-fixed tissues and bone specimens.
• Analyzed both trio and duo pedigrees.

Main Results:

• EFMrep yielded significantly higher likelihood ratios (LRs) in MD and HD duos compared to other software.
• In trios, Familias produced higher LRs for MD samples, while performance was comparable for HD samples.
• EFMrep maximized LR values in HD trios (60% > 10,000), outperforming EFM (50%) and Familias (40%).

Conclusions:

• PGS demonstrates potential for kinship assessments with LT-DNA specimens.
• Specific software like EFMrep shows advantages in maximizing LRs for degraded samples.
• Further research is needed to fully understand the potential and limitations of PGS in forensic kinship testing.