Polymorphisms of mtDNA control region in Tunisian and Moroccan populations: An enrichment of forensic mtDNA databases with Northern Africa data

https://doi.org/10.1016/j.fsigen.2009.01.014 Get rights and content

Abstract

Current forensic mitochondrial (mt)DNA databases are limited in representative population data of African origin. We investigated HVS-I/HVS-II sequences of 120 Tunisian and Moroccan healthy male donors applying stringent quality criteria to assure high quality of the data and phylogenetic alignment and notation of the sequences. Among 64 Tunisians, 56 different haplotypes were observed and the most common haplotype (16187T 16189C 16223T 16264T 16270T 16278T 16293G 16311C 73G 152C 182T 185T 195C 247A 263G 309.1C 315.1C; haplogroup (hg) L1b) was shared by four individuals. 56 Moroccans could be assigned to 52 different haplotypes where the most common haplotype was of West Eurasian origin with the hg H sequence motif 263G 315.1C and variations in the HVS-II polyC-stretch (309.1C 309.2C) shared by six samples. The majority of the observed haplotypes belong to the west Eurasian phylogeny (50% in Tunisians and 62.5% in Moroccans). Our data are consistent with the current phylogeographic knowledge displaying the occurrence of sub-Saharan haplogroup L sequences, found in 48.4% of Tunisians and 25% of Moroccans as well as the presence of the two re-migrated haplogroups U6 (7.8% and 1.8% in Tunisians and Moroccans, respectively) and M1 (1.6% in Tunisians and 8.9% in Moroccans).

Introduction

North Africa has been colonized in the Upper Palaeolithic [1], followed by the expansion of farming during the Neolithic from the Middle East through Egypt [2]. Since then the North African coast was characterized by several invasions from different populations, e.g. Phoenicians, Romans, Vandals, Byzantines, Arabs, Ottomans, Spanish and French and immigrants from sub-Saharan Africa. The present day make up of the North African population is a result of this admixture as evidenced by the heterogeneous gene pool [3], [4]. In the last thirty years, Italy has been subjected to a continuous flow of immigration from other European, Asian and African countries with a considerable increase in the last ten years. At the beginning of 2007 more than 400,000 immigrants being legal residents in Italy originate from Tunisia and Morocco and it is estimated that some other thousand are clandestine immigrants [5].

The phenomenon of immigration has prominence both in the demographic field, influencing the dynamics of the population and in the socio-economic and legal issue. It has been observed that immigrants involved in criminal cases have increased over the past years as the claims of family reunification. In order to use mtDNA in forensic analysis, as well as other genetic markers, large and high quality cross-reference databases for different populations are required.

Unfortunately, high quality mtDNA databases for forensic purposes are not yet available for some populations. The first release of EMPOP (www.empop.org ) presented more than 5000 mt DNA sequences from various populations worldwide [6]. Thereof, the majority originates from West Eurasia, and another bulk of more than 5000 sequences from the Asian sub-continent has been added in the second release of the database. However, the populations from the African continent are largely underrepresented.

In the current study we present a set of HVS-I/HVS-II haplotypes from Tunisia and Morocco contributing to the worldwide collection of mtDNA sequences for forensic as well as phylogenetic purposes.

Section snippets

DNA samples

A total of 120 unrelated healthy male donors were analyzed in this study. 64 samples came from different coastal and hinterland cities of North Tunisia, while 56 samples are from northern-central Morocco. Informed consent was obtained from all participants.

DNA was isolated from bloodstains using DNA IQ™ Reference Sample kit on the Maxwell 16 System (Promega).

mtDNA typing

The hypervariable regions HVS-I and HVS-II were amplified and sequenced following the protocols of [7], [8]. Sequencing was performed

Haplotypes notation

The forensic community follows specific guidelines for the alignment and notation of mtDNA sequences [14], [15]. These general rules seem to work well except in the vicinity of polycytosine tracts where length variation is observed and where multiple alignments are possible. An attempt to standardize mtDNA nomenclature by a set of hierarchical rules based on maximum parsimony [16] sometimes results in disputable alignments of haplotypes [11]. In this study multiple alignments were performed in

References (29)

  • I. Dupanloup, Effets de l’adoption de l’agriculture et del’elevage sur les populations proche-orientales et africaines,...
  • K. Fadhlaoui-Zid et al.

    Mitochondrial DNA heterogeneity in Tunisian Berbers

    Ann. Hum. Genet.

    (2004)
  • S. Plaza et al.

    Joining the pillars of Hercules: mtDNA sequences show multidirectional gene flow in the western Mediterranean

    Ann. Hum. Genet.

    (2003)
  • ...
  • Cited by (0)

    Paper presented at the DNA in Forensics meeting, Ancona, 27–30 May, 2008.

    View full text