Collaborative Genetic Mapping of 12 Forensic Short Tandem Repeat (STR) Loci on the Human X Chromosome

• NCJ Number: 240797
• Journal: Forensic Science International: Genetics Volume: 6 Issue: 6 Dated: December 2012 Pages: 778-784
• Author(s): Michael Nothnagel; Reinhard Szibor; Oliver Vollrath; Christa Augustin; Jeanett Edelmann; Maria Geppert; Cintia Alves; Leonor Gusmao; Marielle Vennemann; Yiping Hou; Uta-Dorothee Immel; Serena Inturri; Haibo Luo; Sabine Lutz-Bonengel; Carlo Robino; Lutz Roewer; Burkhard Rolf; Juliane Sanft; Jeong Eun Sim; Peter Wiegand; Christian Winkler; Michael Krawczak; Sandra Hering; Kyoung-Jin Shin
• Date Published: December 2012
• Length: 7 pages
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: Ireland

Annotation

In a collaborative family study, the authors used X-STR genotype data from 401 two- and three-generation families to derive valid estimates of the recombination rates between 12 forensic markers widely used in forensic testing, namely DXS10148, DXS10135, DXS8378 (together constituting linkage group I), DXS7132, DXS10079, DXS10074 (linkage group II), DXS10103, HPRTB, DXS10101 (linkage group III), DXS10146, DXS10134 and DXS7423 (linkage group IV).

Abstract

A large number of short tandem repeat (STR) markers spanning the entire human X chromosome have been described and established for use in forensic genetic testing. Due to their particular mode of inheritance, X-STRs often allow easy and informative haplotyping in kinship analyses. Moreover, some X-STRs are known to be tightly linked so that, in combination, they constitute even more complex genetic markers than each STR taken individually. As a consequence, X-STRs have proven particularly powerful in solving complex cases of disputed blood relatedness. However, valid quantification of the evidence provided by X-STR genotypes in the form of likelihood ratios requires that the recombination rates between markers are exactly known. The current study is the first to simultaneously allow for mutation and recombination in the underlying likelihood calculations, thereby obviating the bias-prone practice of excluding ambiguous transmission events from further consideration. The statistical analysis confirms that linkage groups I and II are transmitted independently from one another; whereas, linkage groups II, III and IV are characterized by inter-group recombination fractions that are notably smaller than 50 percent. Evidence was also found for recombination within all four linkage groups, with recombination fraction estimates ranging as high as 2 percent in the case of DXS10146 and DXS10134. (Published Abstract)