1. ¹Center for Genome Information, Department of Environmental Health, University of Cincinnati, Cincinnati, Ohio, USA
2. ²International Health Institute and Department of Community Health, Brown University, Providence, Rhode Island, USA
3. ³Department of Biochemistry, Sultan Qaboos University, Muscat, Oman
4. ⁴Department of Anthropology, University of Florida, Gainesville, Florida, USA
5. ⁵Instituto de Investigaciones en Salud, Universidad de Costa Rica, Costa Rica
6. ⁶Laboratorio Genetika, Curitiba, Brazil
7. ⁷Human Genetics Center, School of Public Health, University of Texas Health Science Center at Houston, Texas, USA

Correspondence: R Deka, Department of Environmental Health, University of Cincinnati, 3223 Eden Avenue, Cincinnati, OH 45267-0056, USA. Tel: +1 513 558 5989; Fax: +1 513 558 4397; E-mail: ranjan.deka@uc.edu

Received 10 June 2002; Revised 26 August 2002; Accepted 27 August 2002.

Abstract

We have studied genetic variation at nine autosomal short tandem repeat loci in 20 globally distributed human populations defined by geographic and ethnic origins, viz., African, Caucasian, Asian, Native American and Oceanic. The purpose of this study is to evaluate the utility and applicability of these nine loci in forensic analysis in worldwide populations. The levels of genetic variation measured by number of alleles, allele size variance and heterozygosity are high in all populations irrespective of their effective sizes. Single- as well as multi-locus genotype frequencies are in conformity with the assumptions of Hardy-Weinberg equilibrium. Further, alleles across the entire set of nine loci are mutually independent in all populations. Gene diversity analysis shows that pooling of population data by major geographic groupings does not introduce substructure effects beyond the levels recommended by the National Research Council, validating the establishment of population databases based on major geographic and ethnic groupings. A network tree based on genetic distances further supports this assertion, in which populations of common ancestry cluster together. With respect to the power of discrimination and exclusion probabilities, even the relatively reduced levels of genetic variation at these nine STR loci in smaller and isolated populations provide an exclusionary power over 99%. However, in paternity testing with unknown genotype of the mother, the power of exclusion could fall below 80% in some isolated populations, and in such cases use of additional loci supplementing the battery of the nine loci is recommended.