Complex kinship testing using the MGIEasy Pa-SNPs genotyping kit

Disaster victim identification and criminal investigations have intensified the demand of complex kinship testing. Compared to close relatives, distant relatives share fewer identical-by-descent genetic segments; therefore, more genetic markers are required to improve the system effectiveness. Driven by the progress of next-generation sequencing, several commercial or in-house panels, including a large number of genetic markers, have been developed and applied in forensic caseworks. However, few efficient panels are available for first cousins (FC) kinship testing. Here, we adopted the MGIEasy Pa-SNPs genotyping kit, a two-step multiplex PCR strategy to detect 2,009 SNPs, and evaluated their system effectiveness in complex kinship analysis. Samples from 10,000 pairs of relatives and unrelated individuals were simulated to evaluate the system power. Simultaneously, real samples were used to further confirm this, including 72 pairs of full siblings (FS), 52 pairs of uncle/aunt/-niece/nephew (UN), 92 pairs of FC, 79 pairs of first cousin once removed (1C1R), and 780 pairs of unrelated individuals. The results showed that this kit was sufficiently powerful in FS, UN, and FC versus unrelated kinship testing and could also discriminate part of 1C1R relatives against unrelated individuals. This method was also powerful in the kinship determination of FS versus UN, FS versus FC, FS versus 1C1R, and UN versus 1C1R kinship testing but had limited power to determine UN versus FC and FC versus 1C1R relationships. This study provides an effective strategy and guidance for complex kinship analysis in forensic practice.