Likelihood Ratio-Based Evaluation of Full-Sibling Relationships Using 23 Autosomal STR Loci in a Thai Population.
Keywords:
likelihood ratio, STR, full-siblings, forensic genetics, kinship analysisAbstract
This study aimed to evaluate the effectiveness of likelihood ratios (LR) in discriminating full-sibling relationships using 23 autosomal Short Tandem Repeat (STR) loci in a Thai population. A survey research by retrospective study was conducted using allelic profile data obtained from a forensic DNA database. A total of 30 pairs were analyzed, comprising 15 full-sibling pairs and 15 unrelated pairs. The Combined Likelihood Ratio (CLR) was calculated for each pair, and statistical analyses were performed using descriptive statistics and the Mann–Whitney U test. Additionally, log₁₀-transformed CLR values and Receiver Operating Characteristic (ROC) curve analysis were used to evaluate discriminatory performance.
The results showed that CLR values in the full-sibling group were substantially higher than those in the unrelated group, with a statistically significant difference (p < 0.001). The median CLR for full-siblings was 8.24 × 10⁶, whereas that for unrelated individuals was 9.39 × 10⁻⁶, with no overlap observed between the two groups. The log₁₀(CLR) distribution demonstrated clear separation, and ROC analysis yielded an area under the curve (AUC) of 1.000, indicating excellent discriminatory power.
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