Usefulness of X-chromosome markers in resolvingrelationships: Report of a court case involvingpresumed half sisters

摘要

A deficiency case of inheritance dispute involved two women that were either half sisters or unrelated. Using 16 standard forensic markers, the likelihood ratio (LR) in favour of the first hypothesis was 701 1 (p=09986); using four unlinked X-chromosome (chr-X) markers (DXS101, HPRT,STRX1, DXS8377), the LR was 495 8 (p=0. 9980). The increase of power in discriminating relationships among females using chr-X markers was investigated by calculating the expected value of the posterior probability that two true half-sisters were half-sisters rather than unrelated for these chr-X marker and autosomal markers with equivalent allele frequency distribution. The mean increase of the posterior probability was included between 19% (HPRTB) and 37% (DXS8377), and was correlated with locus heterozygosity.