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ORIGINAL ARTICLES
NUMBER 1 YEAR 2003
Genetic Differences in Western Romanian Population Between Autochthonous Caucasian Population and an African Origin Subpopulation Group
1 Biochemistry Department
2 Anatomy Department
3 Biophysics Department
Victor Babes University of Medicine and Pharmacy

Correspondence to:
Andrei Motoc
Victor Babes University of Medicine and Pharmacy of Timisoara
RO - 1900 Timisoara, Piata Eftimie Murgu 2, e-mail: amotoc@umft.ro
ABSTRACT
In the last decades, the globalizing process has led to massive and diverse population migrations, one of the consequences being the modification of population structure. From the anthropological point of view it is interesting to observe the genetic combinations of the specific hereditary material of different populations found in the same areas. The starting point of this research is represented by the study of the specific genetic material of different populations that will have to live together.
The present paper investigates the genetic particularities of Western Romanian population, between autochthonous Caucasian population and those of an African origin population group, mainly originating from Sudan. The investigated genetic particularities are based upon the allelic frequencies distribution of three STR (short tandem repeat) loci: TH01, TPOX, CSF1PO. The specific frequencies of the two population groups are compared using the c2 test. The results are compared with those obtained from the comparison between USA Caucasian and African American population groups.
The obtained data show that the genetic profiles distinction between Western Romania autochthonous population and those of the African origin population group is more evident than between USA Caucasian and African American population groups. These data can be a starting point for different origin population homogenizing process surveillance.
INTRODUCTION

Individual genetic differences are investigated by DNA profiling; a specific profile for each individual can be determined. DNA profiling analysis imposes the utilization of some polymorphic markers that have more alleles for the same locus in the population. This population genetic polymorphism is due to the variation in the number of base pairs for some repetitive sequences, spread throughout the entire human genome. From these genetic markers, STRs are utilized the most because of their small dimensions (the repetitive sequence is 2-8 base pair long), their high population polymorphism, low mutation rate and their easy separation and interpretation of alleles.1,2
This article, investigates the allelic distribution of three STR loci: TH01, TPOX and CSF1PO. The TH01 locus has the 11p15.5 chromosome localization, being inside the tyrosine hydroxylase gene. The repeat sequence is represented by AATG, which can be present in all four possible permutations (AGAT, GATA, ATAG, TAGA). The allelic ladder consists of 7 alleles (from 5 to 11) with size between 179 and 203 base pairs. This locus has also two allelic micro variants: 8.3 and 9.3.
The TPOX locus has the 2p25.1-pter chromosome localization, being inside the thyroid peroxidase gene. The allelic ladder consists of 8 alleles (from 6 to 13) with size between 224 and 252 base pairs.
The CSF1PO locus has the 5q33.3-q34 chromosome localization, being inside the c-fms proto-oncogene for CSF-1 receptor gene. The allelic ladder consists of 9 alleles (from 7 to 15) with size between 295 and 327 base pairs. Other known allele for this locus is allele no. 6.
A STR marker can be useful for population studies as long as it meets the Hardy-Weinberg equilibrium for allelic distribution in the studied population.3,4 Therefore, in the last decade, the utilization of STR markers became a current technique for population studies, philogenetic or anthropological studies.9-18

Materials and Methods

102 blood samples from unrelated Western Romania autochthonous individuals and 42 samples from unrelated African origin residents (mainly originating from Sudan) were analyzed. The DNA was extracted using the Promega Wizard Genomicä DNA purification kit. The PCR reaction was performed on a MJ Research thermo-cycler using the specific program for these loci along with the amplification kits PCR Core System and CTT Multiplex primers from Promega Corporation.
Allele separation was performed by denaturing PAGE (polyacrilamide gel electrophoresis) on a Bio-Rad Protean II X-Cell electrophoresis system followed by silver staining. The gels were scanned and interpreted using the Quantity Oneä software from Bio-Rad.5,6
The statistical evaluation of the allelic frequencies for the investigated loci regarding the Hardy-Weinberg equilibrium was performed using the c2 test.7,8 Using the same statistical test, we compared the allelic frequencies of the investigated loci (TH01, TPOX, CSF1PO) for the four population groups (Western Romania autochthonous population and African origin population group, USA Caucasian and African American population groups).

Results and Discussions

The statistical evaluation of the STR loci TH01, TPOX, CSF1PO using the c2 test regarding the genotype frequencies shows values for p as being situated in the interval 0.01<p<0.05 for both population groups (Western Romania autochthon population and African origin population group). This means that both population groups meet Hardy-Weinberg equilibrium and the three investigated loci can be used as STR markers for this study.
The allelic frequencies of the investigated loci for Western Romania autochthonous population, African origin resident population group, USA Caucasian and African American population groups are presented comparatively in Fig 1, Fig 2, Fig 3.
From the data found in these tables one can observe that there are significant differences between allelic frequencies of the studied populations, especially for the 7 and 9.3 alleles of TH01 locus, alleles 7,8,9,10 of TPOX locus and alleles 7,8,12 of CSF1PO locus. The differences between these allelic frequencies are correlated with those between USA Caucasian and African American population groups. Based upon the data shown in Figuress 1-3 we compared using the c2 test the allelic frequencies of the investigated loci for the studied population groups. The results are shown in Fig 4, Fig 5, Fig 6.
Figure 1. Comparison between allelic frequencies of TH01 locus for different populations.
Figure 2. Comparison between allelic frequencies of TPOX locus for different populations.

Figure 3. Comparison between allelic frequencies of CSF1PO locus for different populations.
Figure 4. c2 comparisons between allelic frequencies of TH01 locus for different population groups.

Figure 5. c2 comparisons between allelic frequencies of TPOX locus for different population groups.
Figure 6. c2 comparisons between allelic frequencies of TPOX locus for different population groups.
Comparison of values from figures 4-6 for the two studied populations (Western Romanian autoch- thonous population and African origin resident population group) shows that these two populations are clearly different regarding the allelic distribution for the three studied loci. The difference is similar to that observed in the case between USA Caucasian and African American population groups, and for TPOX and CSF1PO loci this difference is more pronounced.

Conclusions

The genetic study regarding the allelic distribution of the three STR loci investigated reveals distinct genetic profiles for the Western Romanian autochthonous population and African origin resident population group, the distinction being more evident than that for the USA Caucasian and African American population groups.
The allelic distributions of the STR loci, as well as the comparison indexes between the two studied populations represent a useful database both for anthropological studies and genotyping methods.
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