Mitochondrial DNA and Y-chromosome microstructure in Tunisia

Shrouded in history: Unveiling the ways of life of an early Muslim population in Santarém, Portugal (8th- 10th century AD)

In around 716 AD, the city of Santarém, Portugal, was conquered by the Berber and Arab armies that swept the Iberian Peninsula and went on to rule the region until the 12th century. Archaeological excavations in 2007/08 discovered an Islamic necropolis (Avenida 5 de Outubro #2-8) that appears to contain the remains of an early Muslim population in Santarém (8th- 10th century). In this study, skeletal material from 58 adult individuals was analysed for stable carbon (δ13Ccol; δ13Cap), nitrogen (δ15N) and sulphur (δ34S) isotope ratios in bones, and stable oxygen (δ18O), carbon (δ13Cen) and radiogenic strontium (87Sr/86Sr) isotopes in tooth enamel. The results of this study revealed a dietary pattern of predominantly C3-plant and domestic C3-fed herbivore consumption during adulthood (δ13Ccol and δ15N, respectively) but a higher proportion of C4-plant input during childhood (δ13Cen) for some individuals-interpreted as possible childhood consumption of millet porridge, a common practice in North Africa-in those with unorthodox burial types (Groups 1 and 2) that was not practiced in the individuals with canonical burials (Group 3). In this first mobility study of a medieval Muslim population in Portugal, δ18ODW values revealed greater heterogeneity in Groups 1 and 2, consistent with diverse origins, some in more humid regions than Santarém when compared to regional precipitation δ18O data, contrasting the more homogenous Group 3, consistent with the local precipitation δ18O range. Ancient DNA analysis conducted on three individuals revealed maternal (mtDNA) and paternal (Y-chromosome) lineages compatible with a North African origin for (at least) some of the individuals. Additionally, mobility of females in this population was higher than males, potentially resulting from a patrilocal social system, practiced in Berber and Arab communities. These results serve to offer a more detailed insight into the ancestry and cultural practices of early Muslim populations in Iberia.

Mitochondrial DNA and Alzheimer's disease: a first case-control study of the Tunisian population

BACKGROUND

Alzheimer's disease (AD) is the most common neurodegenerative disorder in humans and presents a major health problem throughout the world. The etiology of AD is complex, and many factors are implicated, including mitochondria. Mitochondrial alteration has been proposed as a possible cause of AD. Therefore, several studies have focused on finding an association between inherited mitochondrial DNA variants and AD onset.

METHODS

In this study, we looked, for the first time, for a potential association between mitochondrial haplogroups or polymorphisms and AD in the Tunisian population. We also evaluated the distribution of the major genetic risk factor for AD, the apolipoprotein E epsilon 4 (APOE ε4), in this population. In total, 159 single-nucleotide polymorphisms (SNPs) of mitochondrial DNA haplogroups were genotyped in 254 individuals (58 patients and 196 controls). An additional genotyping of APOE ε4 was performed.

RESULTS

No significant association between mitochondrial haplogroups and AD was found. However, two individual SNPs, A5656G (p = 0.03821, OR = 10.46) and A13759G (p = 0.03719, OR = 10.78), showed a significant association with AD. APOE 4 was confirmed as a risk factor for AD (p = 0.000014).

CONCLUSION

Our findings may confirm the absence of a relation between mitochondrial haplogroups and AD and support the possible involvement of some inherited variants in the pathogenicity of AD.

Insights into the Middle Eastern paternal genetic pool in Tunisia: high prevalence of T-M70 haplogroup in an Arab population

To obtain refreshed insights into the paternal lineages of Tunisian populations, Y-chromosome diversity was assessed in two populations belonging to an Arab genealogical lineage, Kairouan and Wesletia, as well as in four Tunisian Andalusian populations, Testour, Slouguia, Qalaat-El-Andalous and El Alia. The Arabs from Kairouan revealed 73.47% of E-M81 and close affinities with Berber groups, indicating they are likely arabized Berbers, clearly differentiated from the Arabs from Wesletia, who harbored the highest frequency (71.8%) of the Middle Eastern component ever observed in North Africa. In the Tunisian Andalusians, the North African component largely prevailed, followed by the Middle Eastern contribution. Global comparative analysis highlighted the heterogeneity of Tunisian populations, among which, as a whole, dominated a set of lineages ascribed to be of autochthonous Berber origin (71.67%), beside a component of essentially Middle Eastern extraction (18.35%), and signatures of Sub-Saharan (5.2%), European (3.45%) and Asiatic (1.33%) contributions. The remarkable frequency of T-M70 in Wesletia (17.4%) prompted to refine its phylogeographic analysis, allowing to confirm its Middle Eastern origin, though signs of local evolution in Northern Africa were also detected. Evidence was clear on the ancient introduction of T lineages into the region, probably since Neolithic times associated to spread of agriculture.

STAT3 polymorphisms in North Africa and its implication in breast cancer

BACKGROUND

Only a few studies have investigated the association of single nucleotide polymorphisms in STAT3 gene with the susceptibility to cancer and response to chemotherapy. Our aim was to determine the allele frequencies of rs3869550, rs957971, and rs7211777 at the STAT3 gene in North African populations and compare them to 1000 genomes populations, and to investigate their relation with cancer.

METHODS

The targeted SNPs have been analyzed in six Tunisian populations and a sample of Libyans using TaqMan® Assay. The results were compared to 1000 Genomes Project population samples. Targeting of the regions encompassing the three SNPs by micro-ARN was assessed using miR databases.

RESULTS

The analysis of the 3 SNPs showed that North African populations were close to South Asians. As expected, African populations presented a significant frequency of the ancestral CCG haplotype in contrast to other populations where the fully derived TGA haplotype was more frequent. The presence and diversity of rare haplotypes at STAT3 in North African populations could have been generated by recombination between the two major haplotypes. A screening of the micro-RNA databases showed that the STAT3 region with the mutated allele of rs7211777 (G>A) could be targeted by miR hsa-miR-3606-5p, which also targets genes involved in breast cancer.

Berbers and Arabs: Tracing the genetic diversity and history of Southern Tunisia through genome wide analysis

OBJECTIVES

Tunisia has been a crossroads for people from Africa, Europe, and the Middle East since prehistoric times. At present, it is inhabited by two main ethnic groups, Arabs and Berbers, and several minorities. This study aims to advance knowledge regarding their genetic structure using new population samplings and a genome-wide approach.

MATERIALS AND METHODS

We investigated genomic variation, estimated ancestry components and dated admixture events in three Berber and two Arab populations from Southern Tunisia, mining a dataset including Middle Eastern, sub-Saharan, and European populations.

RESULTS

Differences in the proportion of North African, Arabian, and European ancestries and the varying impact of admixture and isolation determined significant heterogeneity in the genetic structure of Southern Tunisian populations. Admixture time estimates show a multilayer pattern of admixture events, involving both ethno-linguistic groups, which started around the mid XI century and lasted for nearly five centuries.

DISCUSSION

Our study provides evidence that the relationships between genetic and cultural diversity of old and new inhabitants of North Africa in southern Tunisia follow different patterns. The Berbers seem to have preserved a significant part of their common genomic heritage despite Islamization, Arab cultural influence, and linguistic diversity. Compared to Morocco and Algeria, southern Tunisian Arabs have retained a higher level of Arabian ancestry. This is more evident in the semi-nomad R'Baya, who have kept their original Bedouin lifestyle, than in the population from Douz, who have undergone multiple events of stratification and admixture.

Consanguinity and Inbreeding in Health and Disease in North African Populations

North Africa is defined as the geographical region separated from the rest of the continent by the Sahara and from Europe by the Mediterranean Sea. The main demographic features of North African populations are their familial structure and high rates of familial and geographic endogamy, which have a proven impact on health, particularly the occurrence of genetic diseases, with a greater effect on the frequency and spectrum of the rarest forms of autosomal recessive genetic diseases. More than 500 different genetic diseases have been reported in this region, most of which are autosomal recessive. During the last few decades, there has been great interest in the molecular investigation of large consanguineous North African families. The development of local capacities has brought a substantial improvement in the molecular characterization of these diseases, but the genetic bases of half of them remain unknown. Diseases of known molecular etiology are characterized by their genetic and mutational heterogeneity, although some founder mutations are encountered relatively frequently. Some founder mutations are specific to a single country or a specific ethnic or geographic group, and others are shared by all North African countries or worldwide. The impact of consanguinity on common multifactorial diseases is less evident.

A genome wide SNP genotyping study in the Tunisian population: specific reporting on a subset of common breast cancer risk loci

Background

Breast cancer is the most common cancer in women worldwide. Around 50% of breast cancer familial risk has been so far explained by known susceptibility alleles with variable levels of risk and prevalence. The vast majority of these breast cancer associated variations reported to date are from populations of European ancestry. In spite of its heterogeneity and genetic wealth, North-African populations have not been studied by the HapMap and the 1000Genomes projects. Thus, very little is known about the genetic architecture of these populations.

Methods

This study aimed to investigate a subset of common breast cancer loci in the general Tunisian population and to compare their genetic composition to those of other ethnic groups. We undertook a genome-wide haplotype study by genotyping 135 Tunisian subjects using the Affymetrix 6.0-Array. We compared Tunisian allele frequencies and linkage disequilibrium patterns to those of HapMap populations and we performed a comprehensive assessment of the functional effects of several selected variants.

Results

Haplotype analyses showed that at risk haplotypes on 2p24, 4q21, 6q25, 9q31, 10q26, 11p15, 11q13 and 14q32 loci are considerably frequent in the Tunisian population (> 20%). Allele frequency comparison showed that the frequency of rs13329835 is significantly different between Tunisian and all other HapMap populations. LD-blocks and Principle Component Analysis revealed that the genetic characteristics of breast cancer variants in the Tunisian, and so probably the North-African populations, are more similar to those of Europeans than Africans.

Using eQTl analysis, we characterized rs9911630 as the most strongly expression-associated SNP that seems to affect the expression levels of BRCA1 and two long non coding RNAs (NBR2 and LINC008854). Additional in-silico analysis also suggested a potential functional significance of this variant.

Conclusions

We illustrated the utility of combining haplotype analysis in diverse ethnic groups with functional analysis to explore breast cancer genetic architecture in Tunisia. Results presented in this study provide the first report on a large number of common breast cancer genetic polymorphisms in the Tunisian population which may establish a baseline database to guide future association studies in North Africa.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5133-8) contains supplementary material, which is available to authorized users.

Ancient and recent Middle Eastern maternal genetic contribution to North Africa as viewed by mtDNA diversity in Tunisian Arab populations

OBJECTIVES

Through previous mitochondrial DNA studies, the Middle Eastern maternal genetic contribution to Tunisian populations appears limited. In fact, most of the studied communities were cosmopolitan, or of Berber or Andalusian origin. To provide genetic evidence for the actual contribution of Middle Eastern mtDNA lineages to Tunisia, we focused on two Arab speaking populations from Kairouan and Wesletia known to belong to an Arab genealogical lineage.

MATERIALS AND METHODS

A total of 114 samples were sequenced for the mtDNA HVS-I and HVS-II regions. Using these data, we evaluated the distribution of Middle Eastern haplogroups in the study populations, constructed interpolation maps, and established phylogenetic networks allowing estimation of the coalescence time for three specific Middle Eastern subclades (R0a, J1b, and T1).

RESULTS

Both studied populations displayed North African genetic structure and Middle Eastern lineages with a frequency of 12% and 28.12% in Kairouan and Wesletia, respectively. TMRCA estimates for haplogroups T1a, R0a, and J1b in Tunisian Arabian samples were around 15 000 YBP, 9000 to 5000 YBP, and 960 to 600 YBP, respectively.

CONCLUSIONS

The Middle Eastern maternal genetic contribution to Tunisian populations, as to other North African populations, occurred mostly in deep prehistory. They were brought in different migration waves during the Upper Paleolithic, probably with the expansion of Iberomaurusian culture, and during Epipaleolithic and Early Neolithic periods, which are concomitant with the Capsian civilization. Middle Eastern lineages also came to Tunisia during the recent Islamic expansion of the 7th CE and the subsequent massive Bedouin migration during the 11th CE.

Carriers of mitochondrial DNA macrohaplogroup R colonized Eurasia and Australasia from a southeast Asia core area

BACKGROUND

The colonization of Eurasia and Australasia by African modern humans has been explained, nearly unanimously, as the result of a quick southern coastal dispersal route through the Arabian Peninsula, the Indian subcontinent, and the Indochinese Peninsula, to reach Australia around 50 kya. The phylogeny and phylogeography of the major mitochondrial DNA Eurasian haplogroups M and N have played the main role in giving molecular genetics support to that scenario. However, using the same molecular tools, a northern route across central Asia has been invoked as an alternative that is more conciliatory with the fossil record of East Asia. Here, we assess as the Eurasian macrohaplogroup R fits in the northern path.

RESULTS

Haplogroup U, with a founder age around 50 kya, is one of the oldest clades of macrohaplogroup R in western Asia. The main branches of U expanded in successive waves across West, Central and South Asia before the Last Glacial Maximum. All these dispersions had rather overlapping ranges. Some of them, as those of U6 and U3, reached North Africa. At the other end of Asia, in Wallacea, another branch of macrohaplogroup R, haplogroup P, also independently expanded in the area around 52 kya, in this case as isolated bursts geographically well structured, with autochthonous branches in Australia, New Guinea, and the Philippines.

CONCLUSIONS

Coeval independently dispersals around 50 kya of the West Asia haplogroup U and the Wallacea haplogroup P, points to a halfway core area in southeast Asia as the most probable centre of expansion of macrohaplogroup R, what fits in the phylogeographic pattern of its ancestor, macrohaplogroup N, for which a northern route and a southeast Asian origin has been already proposed.

Mitochondrial DNA analysis of Tunisians reveals a mosaic genetic structure with recent population expansion

Tunisia is a country of great interest for human population genetics due to its strategic geographic position and rich human settlement history. These factors significantly contributed to the genetic makeup of present-day Tunisians harbouring components of diverse geographic origins. Here, we investigated the genetic structure of Tunisians by performing a mitochondrial DNA (mtDNA) comparison of 15 Tunisian population groups, in order to explore their complex genetic landscape. All Tunisian data were also analysed against 40 worldwide populations. Statistical results (Tajima's D and Fu's F_S tests) suggested recent population expansion for the majority of studied populations, as well as showed (AMOVA test) that all populations were significantly different from each other, which is evidence of population structure even if it is not guided by geographic and ethnic effects. Gene flow analysis revealed the assignment of Tunisians to multiple ancestries, which agrees with their genetic heterogeneity. The resulting picture for the mtDNA pool confirms the evidence of a recent expansion of the Tunisian population and is in accordance with a mosaic structure, composed by North African, Middle Easterner, European and Sub-Saharan lineages, resulting from a complex settlement history.

On the origin of Iberomaurusians: new data based on ancient mitochondrial DNA and phylogenetic analysis of Afalou and Taforalt populations

The Western North African population was characterized by the presence of Iberomaurusian civilization at the Epiplaeolithic period (around 20,000 years before present (YBP) to 10,000 YBP). The origin of this population is still not clear: they may come from Europe, Near East, sub-Saharan Africa or they could have evolved in situ in North Africa. With the aim to contribute to a better knowledge of the settlement of North Africa we analysed the mitochondrial DNA extracted from Iberomaurusian skeletons exhumed from the archaeological site of Afalou (AFA) (15,000-11,000 YBP) in Algeria and from the archaeological site of Taforalt (TAF) (23,000-10,800 YBP) in Morocco. Then, we carried out a phylogenetic analysis relating these Iberomaurusians to 61 current Mediterranean populations. The genetic structure of TAF and AFA specimens contains only North African and Eurasian maternal lineages. These finding demonstrate the presence of these haplotypes in North Africa from at least 20,000 YBP. The very low contribution of a Sub-Saharan African haplotype in the Iberomaurusian samples is confirmed. We also highlighted the existence of genetic flows between Southern and Northern coast of the Mediterranean.

History of settlement of villages from Central Tunisia by studying families sharing a common founder Glycogenosis type III mutation

Glycogen storage disease type III (GSD III; Cori disease; Forbes disease) is an autosomal recessive inherited metabolic disorder resulting from deficient glycogen debrancher enzyme activity in liver and muscle. In this study, we focused on a single AGL gene mutation p.W1327X in 16 Tunisian patients from rural area surrounding the region of Mahdia in Central Tunisia. This constitutes the largest pool of patients with this mutation ever described. This study was performed to trace the history of the patients' ancestries in a single region. After extraction of genomic DNA, exon 31 of AGL gene was sequenced. The patients were investigated for the hypervariable segment 1 of mitochondrial DNA and 17 Y-STR markers. We found that the p.W1327X mutation was a founder mutation in Tunisia Analysis of maternal lineages shows an admixture of autochthonous North African, sub-Saharan and a predominance of Eurasian haplogroups. Heterogeneity of maternal haplogroups indicates an ancient settlement. However, paternal gene flow was highly homogeneous and originates from the Near East. We hypothesize that the p.W1327X mutation was introduced into the Tunisian population probably by a recent migration event; then the mutation was fixed in a small region due to the high rate of consanguineous marriages and genetic drift. The screening for this mutation should be performed in priority for GSD III molecular diagnosis, for patients from the region of Mahdia and those from regions sharing the same settlement history.

Genetic Heterogeneity in Algerian Human Populations

The demographic history of human populations in North Africa has been characterized by complex processes of admixture and isolation that have modeled its current gene pool. Diverse genetic ancestral components with different origins (autochthonous, European, Middle Eastern, and sub-Saharan) and genetic heterogeneity in the region have been described. In this complex genetic landscape, Algeria, the largest country in Africa, has been poorly covered, with most of the studies using a single Algerian sample. In order to evaluate the genetic heterogeneity of Algeria, Y-chromosome, mtDNA and autosomal genome-wide makers have been analyzed in several Berber- and Arab-speaking groups. Our results show that the genetic heterogeneity found in Algeria is not correlated with geography or linguistics, challenging the idea of Berber groups being genetically isolated and Arab groups open to gene flow. In addition, we have found that external sources of gene flow into North Africa have been carried more often by females than males, while the North African autochthonous component is more frequent in paternally transmitted genome regions. Our results highlight the different demographic history revealed by different markers and urge to be cautious when deriving general conclusions from partial genomic information or from single samples as representatives of the total population of a region.

Study of the T16189C variant and mitochondrial lineages in Tunisian and overall Mediterranean region

The mitochondrial DNA (mtDNA) variant T16189C has been investigated in several metabolic diseases. In this study, we aimed to estimate the frequency of the T16189C variant in Tunisian and other Mediterranean populations and to evaluate the impact of this variant on the phylogeny of Mediterranean populations. Blood sample of 240 unrelated Tunisian subjects were recruited from several Tunisian localities. The hypervariable region 1 of the mtDNA were amplified and sequenced. Additional sequences (N = 4921) from Mediterranean populations were compiled from previous studies. The average frequency of T16189C variant in Tunisia (29%) is similar to that observed in North African and Near Eastern populations. Our findings showed positive correlation of the T16189C variant with Sub-Saharan and North African lineages, while a negative correlation was found with the Eurasian haplogroups, reaching its maximum with the Eurasian haplogroup H. The principal component analyses showed a high internal heterogeneity between Tunisian localities. At the Mediterranean scale, Tunisians are closer to North African (Algerian and Moroccan) and Near Eastern populations (Syrians and Palestinians) than to Europeans.

From Arabia to Iberia: A Y chromosome perspective

At different times during recent human evolution, northern Africa has served as a conduit for migrations from the Arabian Peninsula. Although previous researchers have investigated the possibility of the Strait of Gibraltar as a pathway of migration from North Africa to Iberia, we now revisit this issue and theorize that although the Strait of Gibraltar, at the west end of this corridor, has acted as a barrier for human dispersal into Southwest Europe, it has not provided an absolute seal to gene flow. To test this hypothesis, here we use the spatial frequency distributions, STR diversity and expansion time estimates of Y chromosome haplogroups J1-P58 and E-M81 to investigate the genetic imprints left by the Arabian and Berber expansions into the Iberian Peninsula, respectively. The data generated indicate that Arabian and Berber genetic markers are detected in Iberia. We present evidence that suggest that Iberia has received gene flow from Northwest Africa during and prior to the Islamic colonization of 711A.D. It is interesting that the highest frequencies of Arabia and Berber markers are not found in southern Spain, where Islam remained the longest and was culturally most influential, but in Northwest Iberia, specifically Galicia. We propose that Moriscos' relocations to the north during the Reconquista, the migration of cryptic Muslims seeking refuge in a more lenient society and/or more geographic extensive pre-Islamic incursions may explain the higher frequencies and older time estimates of mutations in the north of the Peninsula. These scenarios are congruent with the higher diversities of some diagnostic makers observed in Northwest Iberia.

Sousse: extreme genetic heterogeneity in North Africa

The male genetic landscape of the territory currently known as Tunisia is hampered by the scarcity of data, especially from cosmopolitan areas such as the coastal city of Sousse. In order to alleviate this lacuna, 220 males from Sousse were examined, for the first time, for more than 50 Y-chromosome single-nucleotide polymorphisms (Y-SNPs) markers and compared with 3099 individuals from key geographically targeted locations in North Africa, Europe and the Near East. The paternal lineages observed belong to a common set of Y haplogroups previously described in North Africa. In addition to the prominent autochthonous North African E-M81 haplogroup which is exclusively represented by its subclade E-M183 (44.55% of Y-chromosomes), a number of Near Eastern Neolithic lineages including E-M78, J-M267 and J-M172 account for 39% of the Y-chromosomes detected. Principal component analysis based on haplogroup frequencies, multidimensional scaling based on Rst genetic distances and analyses of molecular variance using both Y-chromosome short tandem repeat haplotypes and Y-SNP haplogroup data revealed that the Tunisian and North African groups, as a whole, are intra- and inter-specific diverse with Sousse being highly heterogeneous.

Phylogeny and genetic structure of Tunisians and their position within Mediterranean populations

Tunisia is located at the crossroads of Europe, the Middle East and Sub-Saharan Africa. This position might lead to numerous waves of migrations, contributing to the current genetic landscape of Tunisians. In this study, we analyzed 815 mitochondrial DNA (mtDNA) sequences from Tunisia in order to characterize the mitochondrial DNA genetic structure of this region, to construct the processes for its composition and to compare it to other Mediterranean populations. To that end, additional 4206 mtDNA sequences were compiled from previous studies performed in African (1237), Near Eastern (231) and European (2738) populations. Both phylogenetic and statistical analyses were performed. This study confirmed the mosaic genetic structure of the Tunisian population with the predominance of the Eurasian lineages, followed by the Sub-Saharan and North African lineages. Among Tunisians, the highest haplogroup and haplotype diversity were observed in particular in the Capital Tunis. No significant differentiation was observed between both geographical (Northern versus Southern Tunisia) and different ethnic groups in Tunisia. Our results highlight the presence of outliers and most frequent unique sequences in Tunisia (10.2%) compared to 45 Mediterranean populations. Phylogenetic analysis showed that the majority of Tunisian localities were closer to North Africans and Near Eastern populations than to Europeans. The exception was found for Berbers from Jerba which are clustered with Sardinians and Valencians.

Genome-wide and paternal diversity reveal a recent origin of human populations in North Africa

The geostrategic location of North Africa as a crossroad between three continents and as a stepping-stone outside Africa has evoked anthropological and genetic interest in this region. Numerous studies have described the genetic landscape of the human population in North Africa employing paternal, maternal, and biparental molecular markers. However, information from these markers which have different inheritance patterns has been mostly assessed independently, resulting in an incomplete description of the region. In this study, we analyze uniparental and genome-wide markers examining similarities or contrasts in the results and consequently provide a comprehensive description of the evolutionary history of North Africa populations. Our results show that both males and females in North Africa underwent a similar admixture history with slight differences in the proportions of admixture components. Consequently, genome-wide diversity show similar patterns with admixture tests suggesting North Africans are a mixture of ancestral populations related to current Africans and Eurasians with more affinity towards the out-of-Africa populations than to sub-Saharan Africans. We estimate from the paternal lineages that most North Africans emerged ∼15,000 years ago during the last glacial warming and that population splits started after the desiccation of the Sahara. Although most North Africans share a common admixture history, the Tunisian Berbers show long periods of genetic isolation and appear to have diverged from surrounding populations without subsequent mixture. On the other hand, continuous gene flow from the Middle East made Egyptians genetically closer to Eurasians than to other North Africans. We show that genetic diversity of today's North Africans mostly captures patterns from migrations post Last Glacial Maximum and therefore may be insufficient to inform on the initial population of the region during the Middle Paleolithic period.

Introducing the Algerian mitochondrial DNA and Y-chromosome profiles into the North African landscape

North Africa is considered a distinct geographic and ethnic entity within Africa. Although modern humans originated in this Continent, studies of mitochondrial DNA (mtDNA) and Y-chromosome genealogical markers provide evidence that the North African gene pool has been shaped by the back-migration of several Eurasian lineages in Paleolithic and Neolithic times. More recent influences from sub-Saharan Africa and Mediterranean Europe are also evident. The presence of East-West and North-South haplogroup frequency gradients strongly reinforces the genetic complexity of this region. However, this genetic scenario is beset with a notable gap, which is the lack of consistent information for Algeria, the largest country in the Maghreb. To fill this gap, we analyzed a sample of 240 unrelated subjects from a northwest Algeria cosmopolitan population using mtDNA sequences and Y-chromosome biallelic polymorphisms, focusing on the fine dissection of haplogroups E and R, which are the most prevalent in North Africa and Europe respectively. The Eurasian component in Algeria reached 80% for mtDNA and 90% for Y-chromosome. However, within them, the North African genetic component for mtDNA (U6 and M1; 20%) is significantly smaller than the paternal (E-M81 and E-V65; 70%). The unexpected presence of the European-derived Y-chromosome lineages R-M412, R-S116, R-U152 and R-M529 in Algeria and the rest of the Maghreb could be the counterparts of the mtDNA H1, H3 and V subgroups, pointing to direct maritime contacts between the European and North African sides of the western Mediterranean. Female influx of sub-Saharan Africans into Algeria (20%) is also significantly greater than the male (10%). In spite of these sexual asymmetries, the Algerian uniparental profiles faithfully correlate between each other and with the geography.