Analysis of Trio Half Sibling Testing.

Objectives: To establish an analytical method for half sibling testing involving common three relatives' participation.

Methods: Based on the half sibling testing scenarios with the known biological mother, grandfather or uncle, and two unidentified controversial half siblings participating, two opposing hypotheses were set. Lineage reconstruction according to Mendel's law of heredity was carried out, and the calculation formula of the half sibling kinship index was derived. Verification of actual cases was carried out and the results were compared with duo half sibling testing.

Results: In the scenarios of the known biological mother, grandfather and uncle participating in half sibling testing, the kinship calculation formulae of 54, 91 and 99 genotype combinations for kinship index calculation were deduced respectively. The actual cases showed higher kinship indexes in trio half sibling testing compared with duo half sibling testing.

Conclusions: It is beneficial to obtain more genetic information for family reconstruction and improvement of the strength of genetic evidence for half sibling testing by adding known relatives.