A study of 17 short tandem repeat loci mutation in Thai population

Abstract

Background : In paternity testing, differences at genetic loci between the alleged parent and the child would lead to the exclusion of biological paternity. Although rare, transmission inconsistent in paternity testing or single mismatches in DNA profiles may occur, possibly due to either germline or somatic mutation. When single locus discrepancy is present, the mutant allele is hypothesized that mutation occurs possibly in either father or mother.

Objective : The objective of this paper is to report the mutation events related to many short tandem repeat (STR) loci that are frequently used and applied in various scenarios of forensic statistics.

Design : A descriptive study.

Setting : Forensic Serology and DNA, Department of Forensic Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

Materials and Methods : In all, 11,280 meiosis transmissions from 630 paternity testing cases were investigated in Thai population from 2004 to 2010. Each locus was counted and analyzed as percentage of maternal or paternal mutation rate with 95% confidence interval. The mutation was described as the losses or gains of the repeat units.

Results : There were 24 mutations at 10 loci. The observed mutation rate was ranged as 1.3 - 6.6 × 10^-3(10 STR loci) per locus per gamete per generation. The mutation was more frequently presented in the paternal than the maternal germline.

Conclusion : This is the preliminary study of mutation rate of STR loci observed in Thai population. The overall mutation rate is 1.9 × 10^-3 per locus per gamete per generation. This mutation information is useful for forensic statistics to provide more accuracy STR calculation results.