Polymorphisms of mtDNA control region in Tunisian and Moroccan populations: An enrichment of forensic mtDNA databases with Northern Africa data☆
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
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Paper presented at the DNA in Forensics meeting, Ancona, 27–30 May, 2008.