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Interpretation of Y Chromosome STRs for Missing Persons Cases

NCJ Number
Date Published
June 2022
28 pages

The MPKin-YSTR program was developed to facilitate the Y-STR haplotype analysis through more sophisticated methods than have previously been employed, with the objective of improving the interpretation of complex cases with Y-STR haplotype evidence.



The author reports on the creation of a software program, MPKin-YSTR, to facilitate the Y-STR haplotype analysis, specifically for complex missing persons cases. The Short Tandem Repeat (STR) loci contained in the human Y chromosome, inherited through the paternal line, have been used to assist in various forensic investigations for identification or kinship analysis. Y-STR haplotypes, typed with various commercial testing kits, consist of specific sets of Y-STR loci and have been recorded in databases and scientific literature. Based on those databases, Y-STR haplotype frequencies can be estimated for identification, kinship analysis, and mixture analysis purposes. MPKin-YSTR includes three major functions: Y-STR profile comparisons; the calculation of pedigree likelihood ratio (PLR) for kinship analysis with Y-STR profiles; and drawing mismatch contributions to decide a threshold for determining if two profiles are from the same lineage or not. Research results suggest that the MPKin-YSTR tool should be able to improve the interpretation of complex cases with Y-STR haplotype evidence and increase the amount of biological evidence that can be interpreted.

Date Published: June 1, 2022