Full Sibling Testing Based on NGS-SNP Genotyping Method and IBS Strategy.

Objective To evaluate the effectiveness of single nucleotide polymorphism （SNP） genoty-ping in combination with identity by state （IBS） strategy in full sibling testing. Methods Thirty-five blood samples were collected from a four-generation family. Ninety autosomal SNPs were genotyped using Precision ID Identity Panel. The distribution of IBS scores for full siblings and other relationships were calculated and compared. The relationships were determined using Fisher discriminant function and threshold method, respectively. Results Based on family members and previous research, 44, 30, 111, 71 and 1 000 pairs of full siblings （FS）, grandparent-grandchild （GG）, uncle/aunt-nephew/niece （UN）, first cousins （FC） and unrelated individuals （UI） were obtained, respectively. The average IBS scores were 148, 130, 132, 124 and 120, respectively. Except for the GG and UN pairs, the distribution differences among the other relationships had statistical significance （<0.05）. The false rates of Fisher discriminant function to determine relationships were 1.3%, 22.3%, 17.0% and 38.7% for FS, GG, UN and FC, respectively. Based on the simulation data, the thresholds =128 and =141 were recommended to determine full sibling relationships （the false rate ≤0.05%）. Conclusion The 90 SNP genetic markers included in the Precision ID Identity Panel meet the testing requirements for full sibling relationships. The threshold method based on IBS has a relatively lower false rate and is more flexible.