Allele frequencies of the 10 short tandem repeats (STRs) loci (D16S539, D2S1338, D3S1358, vWA, D18S51, D21S11, D8S1179, D19S433, FGA, THO1) included in the AmpFlSTR SGM Plus kit, were obtained from biological samples from 100 unrelated individual residing in different part of Turkey. The c2 test showed that all these loci agreed with Hardy-Weinberg equilibrium, The results were compared with the previously published data from Turkish and other ethnic groups. Suggest that these loci with their high heterozygosity and combined power of discrimination (PD) values are useful for forensic identifications.
Keywords: Forensic science; AmpFlSTR SGM Plus; Short tandem repeats (STRs); Population genetics; Turkey

 

Subjects. Samples were obtained from 100 unrelated Turkish individuals living in Turkey (12 females, 88 males). Individuals were selected from seven geographical region of Turkey. From the Marmara Region (11 individuals), Aegean Region (17 individuals), Central Anatolian Region (24 individuals), Eastern Anatolian Region (16 individuals), Black Sea Region (16 individuals), Mediterranean Region (seven individuals) and Southeastern Region (nine individuals) (Figure 1).
DNA Extraction and Typing. Genomic DNA was isolated from blood, tissue, saliva, hair and semen samples using the phenol-chloroform isoamyl alcohol method [1] [AmpFlSTR SGM Plus™ Polymerase Chain Reaction (PCR) Amplification Kit user manual, 2001]. Multiplex PCR, using 1-2 ng target DNA, was performed with the GeneAmp PCR system 9700 using the AmpFlSTR SGM Plus™ kit (Applied Biosystems Division/Perkin-Elmer, Foster City, CA, USA) according to the manufacturer’s instructions. The loci D16S539, D2S1338, D3S1358, vWA, D18S51, D21S11, D8S1179, D19S433, FGA, THO1 were co-amplified. loci. The results were analyzed using Gene Scan analysis version 3.1.2 software and genotypes were determined by comparison to allelic ladder using Genotyper DNA fragment analysis version 2.0 software (Applied Biosystems/Perkin Elmer).
Analysis of Data. Evaluation of the Hardy-Weinberg equilibrium expectations was carried out using the Fisher’s exact t-test. Further calculation of statistical parameters of forensic interest and population differentiation tests were conducted using the Arlequin 2.0 software package [2].

 

 

Fig.1 Map of Turkey showing its all geographical regions.

 
Results and discussion:Allele frequencies for 10 short tandem repeat (STR) loci and parameters of genetic and forensic interest are presented in Table 1. In the Turkish population, the D3S1358 locus allele 16 (0.556), vWA locus allele 17 (0.486), D16S539 locus allele 11 (0.555), D2S1338 locus allele 17 (0.412), D8S1179 locus allele 13 (0.483), D21S11 locus allele 30 (0.407), D18S51 locus allele 14 (0.349), D19S433 locus allele 14 (0.385), THO1 locus allele 6 (0.604), FGA locus allele 22 (0.460), are the most common alleles. The frequencies ranged from 0.005 to 0.604. The Fisher’s exact t-test results indicated that the loci were in Hardy-Weinberg equilibrium. The most discriminating loci, according to their power of exclusion (PE) values, were D2S1338 and D18S51, whereas THO1 and D3S1358 turned out to be the least discriminating loci. The heterozygosity of the 10 STR loci screened in this study ranged from 0.77 to 0.89, indicating that these loci could be used in determination of identity because of the high heterozygosity. The 10 loci have a power of discrimination (PD) 0.99999999999988 and the combined power of exclusion (PE) is 0.999994 in Turkey. The probability of identity across all 10 loci was estimated as 1 in 8.33 trillion. Thus, the PD value estimated for the Turkish population was highly significant.
On comparison of the observed allele frequencies with previously published data from Turkey [3-9], we found no statistically significant difference for all STRs (p >0.05). Allele 22 of vWA and allele 9 of the D19S433 locus were detected in Turkish individuals, and are absent in Chinese, North and West African and Czech populations [10-13]. The observed combined PD and PE values were also compared with the published populations [10-13]. The combined PE value (0.999994) for Turks was higher than for Chinese (0.999949), Czech (0.999971) and North African (0.999522) populations, but lower than for West Africans (0.99999946). The combined PD value in the Turkish population also seems to be a little higher than in the Chinese (0.999999999997) and the Czech (0.99999999999939), and a little lower than in North African (0.99999999999999959) and West African (0.99999999999999999952) populations.
In conclusion, our results show that 10 STR loci (D16S539, D2S1338, D3S1358, vWA, D18S51, D21S11, D8S1179, D19S433, FGA, THO1) are useful markers for personal identification and forensic case work in the Turkish population.