A paternity case with apparently conflicting multilocus and single-locus DNA typing results

Area of Science:

• Forensic Genetics
• Molecular Biology
• Population Genetics

Background:

• Paternity testing relies on DNA analysis to establish biological relationships.
• Conflicting DNA results can arise from different analytical methods or complex genetic profiles.
• Variable Number of Tandem Repeats (VNTR) and multilocus DNA fingerprinting are established forensic techniques.

Purpose of the Study:

• To resolve a complex paternity dispute with conflicting DNA typing results.
• To evaluate the utility of combining data from VNTR analysis and multilocus DNA fingerprinting.
• To demonstrate the validity of summing log likelihoods for unlinked genetic loci.

Main Methods:

• DNA typing using thirteen VNTR systems.
• Initial multilocus DNA analysis utilizing the oligonucleotide probe (CAC)5.
• Application of a dual analytical approach incorporating both methods.
• Calculation of a joint likelihood ratio to reconcile discordant findings.

Main Results:

• Multilocus analysis initially suggested non-paternity due to low aberrant bands and high band-sharing.
• VNTR analysis provided conflicting data that challenged the initial assessment.
• The combined approach and joint likelihood ratio successfully resolved the case.
• Summation of log likelihoods was validated even without linkage information.

Conclusions:

• A dual DNA typing approach can resolve complex paternity cases with conflicting results.
• The joint likelihood ratio is a robust method for integrating data from different DNA analyses.
• Statistical methods for combining evidence from unlinked genetic markers are reliable in forensic casework.