Browsing by Author "Middleton, D."
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- Distribution of HLA alleles in Portugal and Cabo Verde. Relationships with the slave trade routePublication . Spínola, Hélder; Brehm, A.; Williams, F.; Jesus, J.; Middleton, D.HLA-A,-B, and -DR frequencies were analysed in populations from Portugal and the Madeira and Cabo Verde Archipelagos, aiming to characterize their genetic composition. Portuguese settlers colonized both Archipelagos in the 15th and 16th centuries. Madeira received many sub-Saharan slaves to work in the sugar plantations, and Cabo Verde served as a pivotal market in the Atlantic slave trade and was populated by individuals coming from the Senegambia region of the West African coast. The population of Madeira shows the highest genetic diversity and the presence of alleles and haplotypes usually linked to sub-Saharan populations, the haplotypes accounting for 3±5% of the total. Cabo Verde presents typical markers acknowledged to be of European or IberoMediterranean origin, thus revealing the admixture of European settlers with Sub-Saharan slaves. Altogether the number of European haplotypes reaches 15% of the total. The Portuguese population shows a perceivable and significant heterogeneity both in allele and haplotype frequencies, unveiling a differential input of peoples from different origins. A PCA of the populations studied, plus other relevant ones, clearly shows gene heterogeneity in mainland Portugal as well as the differences and relationships between these populations and Madeira and Cabo Verde.
- HLA class I and II polymorphisms in Azores show different settlements in Oriental and Central islandsPublication . Spínola, H.; Brehm, A.; Bettencourt, B.; Middleton, D.; Bruges-Armas, J.Human leucocyte antigen-A, -B, -Cw, -DRB1, -DQA1 and -DQB1 polymorphisms were examined in the Azorean population. The data were obtained at high-resolution level, using polymerase chain reaction (PCR) with sequence-specific primer, PCR-sequence-specific oligonucleotides and sequence-based typing. The most frequent allele in each locus was: A*0201 (24.5%), B*510101 (9.8%), Cw*0401 (14.8%), DRB1*070101 (18.3%), DQA1*0201 (17.4%) and DQB1*0301 (19.4%). The predominant extended haplotype was A*0202-B*1503-Cw*0202-DRB1*090102-DQA1*0303-DQB1*0202 (1.9%), which was found to be absent in the Portuguese mainland. The present study corroborates historical sources that say the Azores were populated not only by Portuguese but also by other Europeans, mostly Flemish people. Despite dendrogram analysis showing some remote Asian genetic affinities, the lack of specific alleles and haplotypes from those populations does not allow us to conclude for direct influence. Haplotype and allele frequencies in Azores show no homogeneous distribution between Oriental and Central islands of this archipelago. The Oriental islands harbour several haplotypes already found in mainland Portugal and identified as Mediterranean and European. The Central group of islands on the contrary clearly shows an influence of north Europeans (most probably derived from a well-documented Flemish settlement), with much less affinity to mainland Portugal.
- HLA genes in Portugal inferred from sequence-based typing: in the crossroad between Europe and AfricaPublication . Spínola, H.; Middleton, D.; Brehm, A.The human leukocyte antigen-A (HLA-A), -B and -DRB1 polymorphism was examined in the Portuguese population, discriminating between North, Centre and South inhabitants. All data were obtained at high-resolution level, using sequence-based typing. The most frequent allele at each locus was A* 020101 (26%), B* 440301 and B* 510101 (12% each) and DRB1* 070101 (15%). The predominant three-locus haplotype was A*020101B*440301-DRB1*070101 (3.1%), highly frequent in North Portugal (5.4%), lower in Centre (2%) and absent in the South. The present study demonstrates that the Portuguese population has been genetically influenced by Europeans and North Africans, via several historic immigrations. North Portugal seems to concentrate, probably due to the pressure of Arab expansion, an ancient genetic pool originated from several North Africans and Europeans, influences throughout millenniums. South Portugal shows a North African genetic influence, probably of recent origin by means of Berbers accompanying Arab expansion. We found that Centre Portugal is the distribution limit of some alleles and haplotypes that characterize the North or the South of the country. Despite North, Centre and South Portugal not being significantly different in allele frequencies, this study shows that HLA allele and haplotype frequencies are not homogeneous in the country. North and South Portugal show more similarity to North Africans in opposition to Centre which appears closer to Europeans.
- HLA-A, -B and -DRB1 alleles in populations from Madeira, Cabo Verde and three other regions of PortugalPublication . Spínola, H.; Williams, F.; Brehm, A.; Middleton, D.Population from Portugal North (Latitude 41N, Longitude 8W) Portugal South (Latitude 37N, Longitude 8W) Portugal Centre (Latitude 39N, Longitude 8W) Cabo Verde (Latitude 16N, Longitude 24W) Madeira (Latitude 32N, Longitude 17W) consisted of 46 Caucasians, 49 Caucasians, 50 Caucasians, 64 Black and 185 Caucasians respectively. All individuals were from an urban and rural environment and in all populations the grandparents had also lived in the same area. HLA alleles were determined by sequence specific oligonucleotide probes. The results have previously been published in Annuals of Human Geriatrics 66, 285–296, 2002. It was not possible to distinguish DRB1*15 from DRB1*16 and the results are given under DRB1*15.