Evaluation of parentage testing accuracy of child trafficking cases: Combining the exclusion probability and likelihood ratio approaches

Exploring variations and influencing factors of illegal adoption: A comparison between child trafficking and informal adoption

BACKGROUND

Illegal adoption, which mainly includes child trafficking and informal adoption, has long been a prevalent social issue in China. However, the processes and patterns of illegal adoption are not well understood due to the scarcity of data.

OBJECTIVE

The findings are expected to provide insightful clues for the government and the public to better understand the two categories of illegal adoption.

PARTICIPANTS AND SETTING

This study included 4296 trafficking cases and 4499 informal adoption cases between 1949 and 2018. The data came from the 'Baby Coming Back Home' (https://www.baobeihuijia.com) website, which is the most comprehensive commonweal forum established by nongovernmental volunteers for finding missing persons in China.

METHODS

Mathematical statistics and hot spot analysis were used to visualize the spatiotemporal pattern of illegal adoption.

RESULTS

Child trafficking and informal adoption show opposite gender preferences and different age gradients. The numbers of both cases peaked in the early 1990s and then dropped. More than 50 % of all trafficked children were male, whereas approximately 83 % cases of informal adoption were female between 1980 and 2000. Hot spots of illegal adoption have shifted from the cities of the Huai River Basin to the southeastern coastal cities over time, 39.40 % of trafficking cases occurred in rural residential areas, and 52.45 % of informal adoption cases were observed in hospitals.

CONCLUSIONS

Child trafficking and informal adoption are two different ways of adopting children in China. The combination of the one-child policy and the traditional culture of son preference shaped the different characteristics of the illegal adoption of children during a critical period.

Evaluation of a Custom SNP Panel for Identifying and Rectifying of Misjudged Paternity in Deficiency Cases

Parentage testing is routinely performed by genotyping short tandem repeat (STR) through capillary electrophoresis in the present. However, ambiguous or even misjudged paternity based on STRs happens from time to time in cases where only one putative parent is available. We analyzed STR data of 7,818,969 unrelated pairs and 75 close-relative pairs and found that although the probability of a random false match between non-relatives was 4.22 × 10^-6, the incidence of false or ambiguous paternity results between children and first-degree relatives of their true parent was as high as 18.67%. These results highlight the risk of false inclusion of a relative or even non-relatives in parentage testing with STRs. We then validated all ambiguous STR results by targeted sequencing with a custom panel containing 4,830 individual identification single nucleotide polymorphisms (IISNP), found that the ratio of mismatch loci to total SNPs was 1.78-6.95% in close relatives compared with 10.93-13.49% in unrelated pairs. Last, we reported three real cases with undetermined paternity by STRs and rectified them by dissecting with our IISNP panel. These results suggested that high-density IISNP panel can be used to identify and rectify misjudged cases effectively.