Evaluation of Detection Efficiency for Trio Full Sibling Testing.

OBJECTIVES: To study the detection efficiency of trio full sibling with another known full sibling reference added under different number of autosomal STR typing systems. METHODS: Based on 43 detection systems consisting of 13 to 55 representative autosomal STR loci, 10 000 true families (full sibling group) and 10 000 false families (unrelated individual group) were randomly simulated. The full sibling index (FSI) was calculated based on the method of family reconstruction. The cumulative sibling relationship index (CFSI) of 0.000 1 and 10 000 were used as the evaluation thresholds, and the detection efficiency parameters were calculated and compared with the identification of the duo full sibling testing. RESULTS: With the increasing number of STR loci, the error rate and inability of judgement rate gradually decreased; the sensitivity, specificity, correct rate of judgment and other parameters gradually increased, and the system efficiency gradually improved. Under the same detection system, trio full sibling testing showed higher sensitivity, specificity, system efficiency and lower inability of judgement rate compared with duo full sibling testing. When the system efficiency was higher than 0.85 and inability of judgement rate was less than 0.01%, at least 20 STRs should be detected for trio full sibling testing, which was less than 29 STRs required by duo full sibling testing. CONCLUSIONS: The detection efficiency of trio full sibling testing is superior to that of duo full sibling testing with the same detection system, which is an effective identification scheme for laboratories with inadequate detection systems or for materials with limited conditions.

Ethical issues of the research and practice in forensic genetics.

Forensic genetics mainly uses human biological samples as the objects, solves the identification of biological materials related to law by detecting genetic information, provides clues for investigation and evidences for trial, thus facing many ethical issues. This paper put forward the ethical principles in forensic genetics research and practice, and discussed the ethical issues in sample collection, forensic DNA phenotyping, forensic genetic genealogy analysis, forensic DNA database development, paternity and kinship testing, and research data sharing. We suggest that specific ethical requirements should be formulated, the ethical review system should be established for forensic genetics and ethical training for practitioners should be strengthened.

Evaluation of genetic parameters of 23 autosomal STR loci in a Southern Chinese Han population.

AIM: To evaluate the 23 autosomal short tandem repeat (STR) loci included in GoldenEye™ 25 A kit using forensic human identification and paternity testing. SUBJECTS AND METHODS: In total, 3751 unrelated individuals from the Southern Chinese Han population were genotyped with the 5-dye GoldenEye™ 25 A multiplex amplification system. PCR products were separated using arrayed capillary electrophoresis. Allele frequencies and forensic parameters for the 23 autosomal STR loci were statistically analysed. RESULTS: A total of 344 alleles were observed, with corresponding allelic frequencies ranging from 0.0001-0.5519 for the 23 STR loci. No significant deviation from the Hardy-Weinberg equilibrium and linkage disequilibrium was observed. The combined power of discrimination (CPD) was 1-1.6290 × 10-28 and the combined power of exclusion (CPE) was 0.999 999 999 89 and 0.999 999 286 93 for trio and duo cases, respectively. From 3865 meioses, 87 mutation events were discovered. The mutation rate varied from 0-0.00285 for each locus. One-step mutation accounted for 94.25% of total mutations. The ratio of paternal vs maternal mutation was 3.76:1.13 kinds of n/(n + 1) heterozygote genotypes were observed. CONCLUSIONS: The results show that 23 STR loci of GoldenEye™ 25 A kit are highly polymorphic in the Southern Chinese Han population, indicating the kit is suitable for forensic application.