Increasing the confidence in half-sibship determination based upon 15 STR loci

Area of Science:

• Forensic Genetics
• Human Identification
• Population Genetics

Background:

• Half-sibship, where individuals share one parent, is crucial in legal and identification contexts.
• Current methods for determining half-sibling relationships include the combined half-sibship index (CHSI).
• Assessing shared alleles at DNA loci also supports kinship determination.

Purpose of the Study:

• To enhance the specificity of half-sibship testing by combining CHSI with all-shared-alleles (ASA) analysis.
• To evaluate the sensitivity and specificity of this combined approach.

Main Methods:

• Utilized 15 STR loci (Identifiler loci, including CODIS 13) for analysis.
• Simulated 355,620 pairs of half-siblings and 178,815 unrelated pairs across three populations.
• Calculated CHSI and ASA for each simulated pair.

Main Results:

• The combination of CHSI and ASA improved the specificity of half-sibship testing.
• Data allowed for the evaluation of sensitivity and specificity in determining half-sibling relationships.
• Identified inherent uncertainties in indirect kinship testing.

Conclusions:

• Recommends the combined evaluation of CHSI and ASA for more accurate half-sibship determination.
• Highlights the importance of robust methods in forensic and identification genetics.
• Emphasizes the need to address uncertainty in kinship analysis.