Browsing by Author "Middleton, Derek"
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- HLA genes in Madeira Island (Portugal) inferred from sequence-based typing: footprints from different originsPublication . Spínola, Hélder; Bruges-Armas, Jácome; Mora, Marian Gantes; Middleton, Derek; Brehm, AntónioHuman leukocyte antigen (HLA)-A, HLA-B, and HLA-DRB1 polymorphisms were examined in Madeira Island populations. The data was obtained at high-resolution level, using sequence-based typing (SBT). The most frequent alleles at each loci were: A*020101 (24.6%), B*5101 (9.7%), B*440201 (9.2%), and DRB1*070101 (15.7%). The predominant three-loci haplotypes in Madeira were A*020101–B*510101–DRB1*130101 (2.7%) and A*010101–B*0801–DRB1*030101 (2.4%), previously found in north and central Portugal. The present study corroborates historical sources and other genetic studies that say Madeira were populated not only by Europeans, mostly Portuguese, but also sub-Saharan Africans due to slave trade. Comparison with other populations shows that Madeira experienced a stronger African influence due to slave trade than Portugal mainland and even the Azores archipelago. Despite this African genetic input, haplotype and allele frequencies were predominantly from European origin, mostly common to mainland Portugal.
- HLA polymorphisms in Cabo Verde and Guiné-Bissau inferred from sequence-based typingPublication . Spínola, Hélder; Bruges-Armas, Jácome; Middleton, Derek; Brehm, AntónioHuman leukocyte antigen (HLA)-A, -B, and -DRB1 polymorphisms were examined in the Cabo Verde and Guiné-Bissau populations. The data were obtained at high-resolution level, using sequence-based typing. The most frequent alleles in each locus was: A*020101 (16.7% in Guiné-Bissau and 13.5% in Cabo Verde), B*350101 (14.4% in Guiné-Bissau and 13.2% in Cabo Verde), DRB1*1304 (19.6% in Guiné-Bissau), and DRB1*1101 (10.1% in Cabo Verde). The predominant three loci haplotype in Guiné-Bissau was A*2301-B*1503-DRB1*1101 (4.6%) and in Cabo Verde was A*3002-B*350101-DRB1*1001 (2.8%), exclusive to northwestern islands (5.6%) and absent in Guiné-Bissau. The present study corroborates historic sources and other genetic studies that say Cabo Verde were populated not only by Africans but also by Europeans. Haplotypes and dendrogram analysis shows a Caucasian genetic influence in today’s gene pool of Cabo Verdeans. Haplotypes and allele frequencies present a differential distribution between southeastern and northwestern Cabo Verde islands, which could be the result of different genetic influences, founder effect, or bottlenecks. Dendrograms and principal coordinates analysis show that Guineans are more similar to North Africans than other HLA-studied sub-Saharans, probably from ancient and recent genetic contacts with other peoples, namely East Africans.