Effect existence of aging on stutter ratio evaluated via Bayesian inference.

Area of Science:

• Forensic Genetics
• Molecular Biology
• Biostatistics

Background:

• Stutter ratio (SR) in capillary electrophoresis-based DNA typing is crucial for forensic mixture interpretation.
• Current statistical models describe SR stochastic behavior, but objective evidence needs further clarification.
• Understanding factors influencing SR, like aging, can enhance DNA evidence robustness.

Purpose of the Study:

• To investigate the effect of aging on stutter ratio (SR) in DNA typing.
• To apply a Bayesian framework for analyzing age-related changes in SR.
• To provide insights into the stochastic behavior of SR for improved forensic analysis.

Main Methods:

• Collected nail scrapings and clippings from 68 healthy individuals across two age groups: young (0-16 years) and older-adult (>61 years).
• Utilized capillary electrophoresis with GlobalFiler Kit for DNA typing.
• Performed Bayesian modeling using a lognormal distribution with multiple linear regression, considering allele and age-class as explanatory variables.

Main Results:

• The median of the posterior distribution for the age-class parameter was positive across all simple repeat loci.
• For CSF1PO and D7S820 loci, the 95% credible interval of the posterior distribution did not include 0.
• Data indicates a slight increase in stutter ratio (SR) with aging.

Conclusions:

• Aging has a slight but measurable effect on the stutter ratio (SR) in DNA typing.
• The findings contribute to a better understanding of SR stochastic behavior in forensic genetics.
• This research may aid in developing more objective and robust DNA mixture interpretation methods.