Genetic structure and origin of peopling in the Azores islands (Portugal): the view from mtDNA

The Azores islands (Portugal), uninhabited when discovered by Portuguese navigators in the fifteenth century, are located in the Atlantic Ocean 1500 km from the European mainland. The archipelago is formed by nine islands of volcanic origin that define three geographical groups: Eastern (S. Miguel and Sta. Maria), Central (Terceira, Faial, Pico, Graciosa and S. Jorge) and Western (Flores and Corvo). To improve the genetic characterisation of the Azorean population, and to clarify some aspects related to the history of settlement, a study of mtDNA was conducted in the population of the archipelago. The HVRI region was sequenced and specific RFLPs were screened in 146 samples obtained from unrelated individuals with Azorean ancestry (50 from the Eastern group, 60 from the Central group, and 37 from the Western group). Samples were classified into haplogroups based on the information obtained from both sequencing and RFLP analysis. All the analyses performed support the idea that, in the whole group of islands, the majority of mtDNA lineages originated from the Iberian Peninsula, mainly from Portugal (mainland). However contributions from other European populations, especially from Northern Europe, cannot be disregarded. The values obtained for the various diversity parameters in the Azores archipelago indicate that the Azorean population, as a whole, does not exhibit the typical characteristics of an isolated population. The analysis of genetic data by groups of islands showed that the Western group exhibited particular features. The distribution of haplogroups in the Western group is very atypical, being significantly different from what is observed in the Eastern and Central groups. Furthermore, the diversity values are, in general, lower than those observed in other populations used for comparison. African haplogroups were found in all the groups of islands. Therefore the presence of Moorish and African slaves on the islands, as reported in historical sources, is supported by the mtDNA genetic data, especially in the Eastern group. The presence of Jews in the Central group is also supported by the mtDNA data. Neither historical nor genetic data (phylogeography of mtDNA) supports the idea of a differential settlement history for the Western group; however, it is represented in the phylogenies as an isolated branch. The effect of genetic drift, induced by the reduced population size since peopling occurred, has led to a very atypical distribution of haplogroups/haplotypes in this group of islands. We cannot ignore the influence of biodemographic and genetic processes, namely founder effect, genetic drift, migration, and even recent mutational events in the mtDNA lineages of the Azorean populations. Nevertheless, a great part of the variation in the Azorean mtDNA can be explained by the settlement history.

Analysis of human platelet antigen systems in a Moroccan Berber population

The human platelet alloantigen systems HPA-1, -2, -3, -4, -5 and -6 in a Moroccan Berber population from the Amizmiz region were determined by polymerase chain reaction using sequence-specific primers (PCR-SSP). The gene frequencies obtained from these unrelated Berbers were 0 x 747 and 0 x 252 for HPA-1a and -1b; 0 x 817 and 0 x 182 for HPA-2a and -2b; 0 x 682 and 0 x 317 for HPA-3a and -3b; 1 and 0 x 0 for HPA-4a and -4b; 0 x 8616 and 0 x 1383 for HPA-5a and -5b; 1 and 0 x 0 for HPA-6a and -6b. The Berbers have the highest frequency for the 1b, 2b and 5b alleles of all the populations reported to date and also the lowest frequency for the 3b allele.

Gm and Km alleles in two Spanish Pyrenean populations (Andorra and Pallars Sobirà): a review of Gm variation in the Western Mediterranean basin

Two Spanish eastern Pyrenean populations, Andorra and Pallars Sobirà, have been tested for G1m(1,2,3,17), G2m(23), G3m(5,6,10,11,13,14,15,16,21,24,28) and Km(1) immunoglobulin allotypes. Km allele and Gm haplotype frequencies in both samples fit well into the Western Mediterranean and, more strictly, Pyrenean ranges with some peculiarities: Andorra showed an elevated frequency (14.7%) of the typical Asian and European Gm21,28;1,2,17;. haplotype, while Pallars Sobirà was characterized by high values (3.7%) of Gm5*;1,17;., a typical sub-Saharan Gm haplotype. Gm diversity assessed through genetic distance and variance analyses revealed a significant geographic partition (4.3%) of Mediterraneans among south, north-east, and north-west groups. It is interesting to note the relatively low genetic variance (2.1%) found between south and north-western Mediterraneans that could reflect ancient population relationships. More locally, genetic boundaries and diversity analyses failed to indicate any geographic pattern and/or genetic differentiation related with the political border in the Pyrenees. The present pattern of variation in this area is probably the result of genetic isolation processes, in addition to some specific demographic phenomena, in the Pyrenean valleys.

GM and KM immunoglobulin allotypes in a Spanish Pyrenean population: Val d'Aran

Four hundred and thirteen unrelated individuals (202 autochthonous and 211 non-autochthonous) of Val d'Aran (Catalan Pyrenees) have been analysed for the GM and KM immunoglobulin genetic system using the inhibition haemagglutination method. This population was defined by eight GM haplotypes (GM*3 23 5*, GM*3 5*, GM*1,17 21,28, GM*1,2,17 21,28, GM*1,17 5*, GM*1,17 5,6,11,24, GM*1,17 10,11,13,15 and GM*1,17 10,11,13,15,16) inferred from the 17 observed phenotypes. The Val d'Aran population frequencies conform to Hardy-Weinberg expectations. The frequencies of phenotypes and haplotypes show a definite homogeneity between the autochthonous and non-autochthonous people of Val d'Aran and 11 other Pyrenean populations (Mauléon, Macaye, St. Jean Pied de Port, Vallée de L'Ouzom, Gavarnie, Barèges, Luz St. Sauveur, Esparros, Camurac, Capcir and Pays de Sault) that have already been studied for the same allotypes. A factorial correspondence analysis was performed for the 12 autochthonous Pyrenean populations, showing a high frequency of the GM*3 23 5* haplotype in the three Pyrenean regions (Western, Central and Eastern), while the GM*1,17 21,28 haplotype is mainly found in the Central region, GM*3 5* in the Eastern and Western zones, and the GM*1,2,17 21,28 is mainly present in the Central and Eastern populations. The results show a relative regional homogeneity, so there is no evidence of a frequency gradient in the Pyrenean populations for the GM and KM genetic systems. It may, however, be noticed that the Central Pyrenean populations form a group, with one population (Vallée de l'Ouzom) isolated from the rest, probably because of its particular model of inheritance by which the heritage is passed to the first born without sex consideration. It has been possible to point out some differences in the genetic structure of the autochthonous and non-autochthonous Val d'Aran population and to place the autochthonous Aranese group among its Pyrenean neighbours.

Positioning of the autochthonous Aran Valley population among Basque and Pyrenean people by means of ABO, Rh (D) and Duffy blood group determinations

A total of 205 unrelated autochthonous individuals of both sexes from the population of the Aran Valley in the central Pyrenees were tested for ABO, Rh and duffy blood groups. This population is of interest because of its relative geographical and historical isolation and its specific peculiarities, such as its own language. The results show a good correlation between the principal component analysis graphic and the geographic positions of the Basque and Pyrenean populations with which the Aranese population is compared.

Variability of the Rh system in a central Pyrenean population (Aran Valley)

This work describes the results of a survey on the Rhesus system carried out in the autochthonous population of Aran Valley, a small and rather isolated region on the Northern side of the Central Pyrenees. Also, a comparison is made with other geographically and historically related populations in order to discuss the data in terms of the historical origin of this population. The data obtained shows a good agreement between observed and expected values in Hardy-Weinberg equilibrium. The Aranese population also reveals some peculiarities concerning some haplotypes. The comparison with European and non European Mediterranean populations shows a clear genetic distance from Basque populations, and a relative proximity with presumably Celtic ones.