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Specificity of sibship determination using the ABI Identifiler multiplex system
Thomas M Reid1, Caitlin A Wolf, Christopher M Kraemer
1DNA Diagnostics Center, Fairfield, OH 45014, USA. tmr@dnacenter.com
Journal of Forensic Sciences
|December 1, 2004
Summary
Forensic DNA analysis using short tandem repeat (STR) genotyping effectively distinguishes siblings from unrelated individuals. Combined sibship indices (CSIs) provide robust evidence for familial relationships in forensic investigations.
Area of Science:
- Forensic Science
- Genetics
- Molecular Biology
Background:
- Accurate sibling identification is crucial in forensic investigations and paternity testing.
- Short tandem repeat (STR) markers are widely used in human identification due to their high discriminatory power.
Purpose of the Study:
- To evaluate the effectiveness of the ABI Identifiler STR system in differentiating siblings from unrelated individuals.
- To assess the utility of combined sibship indices (CSIs) for confirming familial relationships.
Main Methods:
- Genotyping of 50 known sibling pairs and 50 unrelated pairs using the ABI Identifiler STR system.
- Computation of combined sibship indices (CSIs) for all tested pairs.
- Analysis of allele matching patterns at each locus for both groups.
Main Results:
- Combined sibship indices (CSIs) for known siblings ranged from <10 to >1 billion, while for unrelated pairs, they ranged from 4.5 x 10(-8) to 0.12.
- Approximately 40% of loci showed full allele matching in siblings, compared to 6% in unrelated pairs.
- Approximately 50% of loci showed a single allele match in both sibling and unrelated groups, highlighting the importance of considering multiple loci.
Conclusions:
- The ABI Identifiler STR system and associated CSIs effectively distinguish siblings from unrelated individuals.
- STR analysis provides strong statistical power for determining sibling relationships in forensic contexts.
- The observed allele matching patterns underscore the necessity of comprehensive analysis across multiple STR loci for accurate relationship inference.