www.elsevier.com/locate/forsciint

Forensic Science International 167 (2007) 87–92

Announcement of Population Data

Allele frequencies of 15 autosomal STR loci in the Iraq population with

comparisons to other populations from the middle-eastern region

Filippo Barni a,*, Andrea Berti a, Antonio Pianese a, Antonio Boccellino a,Mark P. Miller b, Aldo Caperna c, Giampietro Lago a

a Carabinieri Scientific Investigation Department of Rome-Molecular Biology and Genetics Unit, Viale di Tor di Quinto 151, 00191 Rome, Italyb Department of Biology, 5305 Old Main Hill, Utah State University, Logan, Utah 84322-5305, USA

c Carabinieri Headquarter, Health Department, Viale Romania 45, 00197 Rome, Italy

Received 30 December 2005; received in revised form 27 January 2006; accepted 4 March 2006

Available online 17 April 2006

Abstract

Allele frequencies for the 15 autosomal STR loci included in the AmpFlSTR1 IdentifilerTM PCR Amplification Kit panel from Applied

Biosystems (D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, TH01, TPOX, CSF1PO, D19S433, D2S1338,

D16S539) and several statistical parameters were estimated from a sample of 103 unrelated individuals, mostly Shia and Sunni Arabs, living in

most of central and southern Iraq provinces. We compared the allele frequency spectrum detected in the Iraqi population to allele frequencies from

11 other data sets from published studies of individuals from Turkey, Iraqi-Kurdistan, Saudi Arabia, Arab Emarates, Oman, Iran, Syria, and Jordan.

Significant global differences in allele frequencies were detected in 9 of the 11 comparisons following sequential Bonferroni corrections.

Comparisons with the two independent panels from Saudi Arabia were not significant after applying Bonferroni corrections, however, low P-values

(P < 0.05) associated with these two contrasts nonetheless suggested that at least slight genetic differences between populations may exist.

# 2006 Elsevier Ireland Ltd. All rights reserved.

Keywords: Iraq population; Shia and Sunni Arabs; STR DNA typing; Population data; Allele frequencies

Population: Buccal cells were collected by oral brushes

(Sterile Omni Swab or Sterile Foam Tipped Swabs, Whatman

International Ltd., Maidstone, UK) from 103 healthy, randomly

chosen individuals deriving from most of Iraq central and

southern provinces (Fig. 1). The number and ethnicity of

individuals were chosen in order to obtain a population sample

resembling the Iraq population structure and to achieve the

highest possible representation of the major ethno-religious and

tribal groups of the Country living in these central and southern

areas. Our sample was mainly constituted by Shia Arabs and,

secondly, by Sunni Arabs. Shia Arabs comprise about 65–70%

of the entire Iraq population while Sunni Arabs represent about

25% of Iraq population (Fig. 2).

DNA extraction: DNA from these samples was extracted

using QIAmp1 DNA Mini Kit (QIAGEN, Hagen, Germany)

according to manufacturer’s instructions.

* Corresponding author. Tel.: +39 347 1849158; fax: +39 02 700412617.

E-mail address: filippobarni@tin.it (F. Barni).

0379-0738/$ – see front matter # 2006 Elsevier Ireland Ltd. All rights reserved.

doi:10.1016/j.forsciint.2006.03.005

DNA quantification: The total amount of human genomic

extracted DNA was determined by using QuantifilerTM Human

DNA Quantification Kit (Applied Biosystems, Foster City, CA,

USA) [1], which employs a TaqMan1 MGB Probe-based

technology (Applied Biosystems, Foster City, CA, USA) on

ABI Prism1 7000 Sequence Detection System (Applied

Biosystems, Foster City, CA, USA).

PCR: Simultaneous amplifications of 16 STR loci (multi-

plexed PCR) were performed by using the AmpFlSTR1

IdentifilerTM PCR Amplification Kit according to the user’s

manual recommendations [2]. The 16 loci amplified in this

study are D3S1358, vWA, FGA, D8S1179, D21S11, D18S51,

D5S818, D13S317, D7S820, TH01, TPOX, CSF1PO,

D19S433, D2S1338, D16S539 and the gender determination

marker, Amelogenin.

Typing: The separation and detection of amplified products

were conducted with the ABI Prism1 3100 Genetic Analyzer

16-capillary array system (Applied Biosystems, Foster City,

CA, USA) following manufacturer’s protocols. Data collection

was performed with Data Collection v. 2.0 software (Applied

Biosystems, Foster City, CA, USA) and samples were analyzed

F. Barni et al. / Forensic Science International 167 (2007) 87–9288

Fig. 1. Iraq administrative map showing the population density and the central and southern governorates where our samples came from (areas included in the black

circle) (Source: UNOSAT, www.unosat.org, United Nations).

by GeneMapper1 v. 3.2 software (Applied Biosystems, Foster

City, CA, USA).

Quality control: Experimental procedures were performed

according to the guidelines of the external blind proficiency test

of the GEDNAP (http://www.gednap.org) [3,4].

Statistical analyses: Several forensic and population

parameters such as the power of discrimination (PD), the a

priori chance of exclusion (CE), the polymorphism information

content (PIC), the paternity index (PI), the random match

probability (RMP) and marker’s observed and expected

heterozygosity (Ho and He, respectively) of the 15 loci were

estimated by using the statistical Microsoft WindowsTM-based

software Popgene v. 1.31 [5] and Cervus v. 2.0 [6,7] while

Hardy-Weinberg equilibrium analysis was performed for each

locus by the Chi-square test (x2).

Fig. 2. Iraq ethno-religious map showing the ethnic and religious population compos

and, secondly, by Sunni Arabs, where our samples came from (areas included in t

A set of interpopulation comparisons of allele frequencies

from this study and 11 additional published population data sets

were performed. Our analyses compared the Iraqi data to data

from Turkey [8,9], Iraqi-Kurdistan (northern Iraq) [10], Saudi

Arabia [11,12], Arabs Emirates [12], Oman [12], Iran [12,13],

Syria [14], and Jordan [15] whenever the same loci studied were

shared. In these cases, allele frequency data reported in these

studies were converted to counts by multiplying allele

frequencies from these publications by reported diploid (2N)

sample sizes. Tests for homogeneity of allele frequencies

between locus-specific data sets were performed using the

computer program R � C (M.P. Miller, available at http://

www.marksgeneticsoftware.net), which implements a Markov

Chain Monte Carlo variation of Fisher’s Exact test [16]. A global

P-value over shared loci from comparisons with each panel was

ition and the central and southern governorates, mostly constituted by Shia Arabs

he black circle) (Source: UNOSAT, www.unosat.org, United Nations).

F. Barni et al. / Forensic Science International 167 (2007) 87–92 89

obtained using Fisher’s Combined Probability Test [17]. Results

of global analyses were interpreted following application of

sequential Bonferroni tests for multiple comparisons [17].

Results and discussion: Allele frequencies and statistical

evaluations of the 15 autosomal STR loci analyzed from the

Iraqi population are reported in Table 1. No deviation of

observed genotype frequencies from those expected according

Table 1

Allele frequencies and statistical parameters of AmpFlSTR1 IdentifilerTM PCR A

Allele D8S1179 D21S11 D7S820 CSF1PO

6 – – – –

7 – – 0.0248 –

8 0.0146 – 0.1881 0.0147

9 0.0049 – 0.0990 0.0343

9.3 – – – –

10 0.0777 – 0.3317 0.2647

11 0.1165 – 0.2079 0.2843

12 0.1359 – 0.1139 0.3284

12.2 – – – –

13 0.2136 – 0.0347 0.0637

13.2 – – – –

14 0.1408 – – 0.0098

14.2 – – – –

15 0.2184 – – –

15.2 – – – –

16 0.0583 – – –

16.2 – – – –

17 0.0194 – – –

18 – – – –

19 – – – –

20 – – – –

20.2 – – – –

21 – – – –

21.2 – – – –

22 – – – –

22.2 – – – –

23 – – – –

23.2 – – – –

24 – – – –

24.2 – – – –

25 – – – –

26 – – – –

27 – 0.0248 – –

28 – 0.1139 – –

28.2 – – – –

29 – 0.2228 – –

29.2 – – – –

30 – 0.2426 – –

30.2 – 0.0149 – –

31 – 0.0396 – –

31.2 – 0.1040 – –

32 – – – –

32.2 – 0.1485 – –

33 – – – –

33.2 – 0.0693 – –

34 – 0.0050 – –

34.2 0.0099 – –

35 0.0050 – –

N 206 206 206 206

Ho 0.777 0.881 0.861 0.755

He 0.849 0.843 0.791 0.739

PI 2.242 4.202 3.597 2.041

RMP 0.056 0.053 0.092 0.129

PD 0.944 0.947 0.908 0.871

to Hardy-Weinberg equilibrium was detected at any of the 15

STR loci (Table 1). All loci showed a high degree of genetic

polymorphism, with observed heterozygosity (Ho) values

ranging from 0.621 (TPOX) to 0.881 (D21S11). The

polymorphism information content (PIC) values ranged from

0.568 for D18S51 to 0.852 for D2S1338, indicating good

informativeness of all STR markers. Overall, these parameters

mplification Kit loci in Iraq population

D3S1358 TH01 D13S317 D16S539

– 0.3058 – –

– 0.1699 – –

– 0.1311 0.2330 0.0340

– 0.2379 0.0388 0.1359

– 0.1359 – –

– 0.0194 0.0534 0.0874

– – 0.2233 0.3544

– – 0.3447 0.2913

– – – –

0.0049 – 0.0534 0.0874

– – – –

0.0388 – 0.0534 0.0097

– – – –

0.2282 – – –

– – – –

0.2379 – – –

– – – –

0.3641 – – –

0.1214 – – –

0.0049 – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

– – – –

206 206 206 206

0.806 0.825 0.767 0.806

0.746 0.789 0.771 0.758

2.577 2.857 2.146 2.577

0.120 0.085 0.089 0.097

0.880 0.915 0.911 0.903

F. Barni et al. / Forensic Science International 167 (2007) 87–9290

Table 1 (Continued )

Allele D8S1179 D21S11 D7S820 CSF1PO D3S1358 TH01 D13S317 D16S539

CE 0.522 0.512 0.410 0.322 0.333 0.399 0.379 0.361

PIC 0.826 0.819 0.757 0.689 0.700 0.752 0.732 0.718

P-value 0.060 0.135 0.393 0.533 0.824 0.936 0.660 0.250

Allele D2S1338 D19S433 vWA TPOX D18S51 D5S818 FGA

6 – – – 0.0049 – – –

7 – – – – – – –

8 – – – 0.5437 – 0.0049 –

9 – – – 0.0825 – 0.0485 –

9.3 – – – – – – –

10 – – – 0.1068 0.0098 0.0631 –

11 – 0.0049 – 0.2427 0.0196 0.3204 –

12 – 0.0922 – 0.0194 0.1471 0.3495 –

12.2 – 0.0097 – – – – –

13 – 0.1845 – – 0.1765 0.2039 –

13.2 – 0.0534 – – – – –

14 – 0.2282 0.0437 – 0.2010 0.0097 –

14.2 – 0.0243 – – – – –

15 0.0243 0.2184 0.0971 – 0.1225 – –

15.2 – 0.0728 – – – – –

16 0.0437 0.0583 0.3204 – 0.1029 – –

16.2 – 0.0437 – – – – –

17 0.2233 0.0097 0.2184 – 0.1029 – –

18 0.1165 – 0.2282 – 0.0588 – 0.0049

19 0.1019 – 0.0680 – 0.0490 – 0.0777

20 0.1796 – 0.0243 – 0.0049 – 0.0631

20.2 – – – – – – –

21 0.0340 – – – 0.0049 – 0.1650

21.2 – – – – – – –

22 0.0388 – – – – – 0.1602

22.2 – – – – – – –

23 0.1311 – – – – – 0.1990

23.2 – – – – – – –

24 0.0583 – – – – – 0.2087

24.2 – – – – – – 0.0049

25 0.0437 – – – – – 0.0728

26 0.0049 – – – – – 0.0340

27 – – – – – – 0.0097

28 – – – – – – –

28.2 – – – – – – –

29 – – – – – – –

29.2 – – – – – – –

30 – – – – – – –

30.2 – – – – – – –

31 – – – – – – –

31.2 – – – – – – –

32 – – – – – – –

32.2 – – – – – – –

33 – – – – – – –

33.2 – – – – – – –

34 – – – – – – –

34.2 – – – – – – –

35 – – – – – – –

N 206 206 206 206 206 206 206

Ho 0.825 0.796 0.748 0.621 0.824 0.728 0.816

He 0.870 0.848 0.785 0.630 0.868 0.731 0.851

PI 2.857 2.451 1.984 1.319 2.841 1.838 2.717

RMP 0.038 0.048 0.093 0.189 0.037 0.125 0.044

PD 0.962 0.952 0.907 0.811 0.963 0.875 0.956

CE 0.578 0.525 0.399 0.579 0.7812 0.314 0.528

PIC 0.852 0.825 0.749 0.579 0.568 0.680 0.829

P-value 0.473 0.344 0.058 0.377 0.399 0.450 0.710

N: number of alleles; Ho: observed heterozigosity; He: expected heterozigosity; PI: paternity index; RMP: random match probability; PD: power of discrimination;

CE: chance of exclusion; PIC: polymorphic information content; P-value: probability value of Chi-square test for Hardy-Weinberg equilibrium.

F. Barni et al. / Forensic Science International 167 (2007) 87–92 91

Table 2

Results of locus-specific and global tests over loci for genetic differentiation between the Iraqi population examined and other middle-eastern populations

Locus P-values from locus-specific contingency table analyses for each comparison

Eastern Anatolia,

Turkeya

Turkeyb Iraqi-

Kurdistanc

Saudi

Arabiad

Saudi

Arabiae

Arabs

Emiratesf

Omang Iranh Irani Syriaj Jordank

D8S1179 0.2790 0.0006 – – 0.3620 0.2138 0.2362 0.1314 0.0612 0.0958 –

D21S11 0.0558 0.2705 0.6063 – 0.9092 0.0215 0.0730 0.5622 0.4264 0.2456 –

D7S820 0.1872 0.1452 0.0773 – 0.2588 0.7204 0.5006 0.0280 0.1049 0.4228 –

CSF1PO 0.4050 0.3428 0.0595 0.1224 0.5310 0.7335 0.3152 0.3412 0.7682 0.1914 0.2576

D3S1358 – 0.0087 0.0996 – 0.7102 0.0970 0.0217 0.0411 0.1723 0.0396 –

TH01 0.3500 0.7788 0.9193 0.9315 0.0531 0.0550 0.0261 0.6529 0.7947 0.6890 –

D13S317 0.0001 0.0002 0.0057 – 0.0420 0.0077 0.0002 0.0010 0.0004 0.0142 –

D16S539 0.0026 0.1446 – – 0.4446 0.8835 0.3881 0.0852 0.6450 0.0344 0.9172

D2S1338 – 0.0344 – – 0.0182 0.0030 0.2033 0.0325 0.0215 – –

D19S433 – 0.0001 – – 0.1094 0.0052 0.0403 0.0256 0.0889 – –

vWA 0.2650 0.0001 0.0135 0.0806 0.8505 0.2186 0.4879 0.0063 0.0403 0.0384 –

TPOX 0.5810 0.1332 0.4341 0.0140 0.1195 0.2361 0.0067 0.6015 0.2716 0.0020 0.0001

D18S51 0.2747 0.5097 – – 0.1278 0.8735 0.7595 0.0972 0.8705 0.9302 –

D5S818 0.9943 0.7158 0.9032 – 0.7014 0.3803 0.0988 0.4181 0.5954 0.9677 –

FGA 0.0823 0.2694 0.5922 – 0.3000 0.3374 0.4425 0.5334 0.7792 0.4214 –

x2 57.27 105.9767 38.39 17.92 44.95 64.95 73.14 73.44 56.22 55.91 21.3065

d.f. 24 30 20 8 30 30 30 30 30 26 6

P-value 0.0002 <0.0001 0.0079 0.0219* 0.0390* <0.0001 <0.0001 <0.0001 0.0026 0.0006 0.0016

P-values indicate the significance of a test for allele frequency homogeneity between the Iraqi population examined and the populations listed at the top of the table. x2

indicates the test statistic derived from use of Fisher’s Combined Probability Test over loci and d.f. indicates degrees of freedom associated with the test. P-values

from the global test over loci are reported on the bottom row of the table.a Reference: [8].b Reference: [9].c Reference: [10].d Reference: [11].e Reference: [12].f Reference: [12].g Reference: [12].h Reference: [12].i Reference: [13].j Reference: [14].k Reference: [15].* Not significant following sequential Bonferroni corrections.

indicated the general utility of this STR loci panel for forensic

personal identification and paternity testing in the Iraq

population, thereby further confirming its efficacy for forensic

practice also in new populations.

Interpopulation comparisons were also performed by using

contingency table analyses and Fisher’s Combined Probability

Test. This investigation permitted us to assess the degree with

which Iraqi individuals are genetically differentiated from

other human populations in the middle-eastern region sur-

rounding or, at least, nearby central and southern Iraq [8–15].

Results of these analyses revealed multiple single loci with

significant allele frequency differences among populations

(Table 2). Furthermore, global analyses performed over loci

indicated that there were significant overall allele frequency

differences between the Iraqi population and 9 of the 11 other

populations used for comparison following use of sequential

Bonferroni corrections (Table 2). The exceptions to this pattern

were the allele frequency spectra detected in two independent

panels of individuals from Saudi Arabia [11,12], where

P-values nonetheless suggested approximately significant

levels of differentiation (P = 0.022 and 0.039 for [11] and

[12], respectively; Table 2).

Collectively, our data indicate that standardized multilocus

STR panels may be an useful forensic tool which can be applied

for identification purposes also in the Iraq population, but the

comparison among this population and other population from

the middle-eastern region demonstrated a remarkable and

statistically significant genetic differentiation across this area.

Hence, our results further suggest that proper DNA databases

should be generated and employed for forensic genetics

calculations, especially in populations where interpopulation

genetic exchange is extremely reduced both due to ethno-

religious and geographical reasons.

Access to the data: The complete data are available to any

interested researcher upon request to berti.an@tiscali.it.

Other remarks: This paper follows the guidelines for

population data requested by the journal [18].

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