HLA alleles in isolated populations from North Spain: Origin of the Basques and the ancient Iberians P. Sanchez-Velasco E. Gomez-Casado J. Martinez-Laso J. Moscoso J. Zamora E. Lowy C. Silvera A. Cemborain F. Leyva-Cobia ´n A. Arnaiz-Villena Authors’ affiliations: P. Sanchez-Velasco 2 , E. Gomez-Casado 1 , J. Martinez-Laso 1 , J. Moscoso 1 , J. Zamora 1 , E. Lowy 1 , C. Silvera 1 , A. Cemborain 2 , F. Leyva-Cobia ´n 2 , A. Arnaiz-Villena 1 1 Department of Immunology and Molecular Biology, Hosp. 12 de Octubre, Universidad Complutense, Madrid, Spain 2 Department of Immunology, Hospital Universitario Marque ´ s. de Valdecilla, Santander, Spain Correspondence to: Prof. Dr Antonio Arnaiz-Villena Departamento de Microbiologia I (Inmunologı ´a) Facultad de Medicina Universidad Complutense Avda. Complutense 28040 Madrid Spain e-mail: aarnaiz@med.ucm.es website: http://chopo.pntic. mec.es/biolmol Abstract: HLA-A, -B, -DRB1, -DQA1 and -DQB1 alleles have been studied in three relatively isolated populations of northern Spain from Cantabria (Pas Valleys inhabitants or Pasiegos and Cabuernigos) and from the Basque Country (Arratia Valley inhabitants). These populations have been compared with neighbouring ones and other Mediterraneans by using neighbour-joining dendrograms and plane genetic distances. The study of relatively isolated populations is informative to test the relationships between languages and genes (1, 2), as it has been shown that the previously described tight correspondence (1) does not hold at a microgeographical level (2). Complete isolation of human populations is nowadays difficult to find, however, there are certain areas of mountainous northern Spain where the isolation of relative human groups is still observed (Fig.1). Culture and language separate groups of people, particularly those studied in this paper. At one side, the Arratia Valley people speak Basque language and is historically integrated within the Basque Country; on the other side, both Pasiegos and Cabuerniga people now speak only Spanish and have been integrated in the Castilian area since the Middle Ages (3–6). Key words: Algerians; Basques; Berbers; Cabuernigos; Cantabrians; Iberians; Moroccans; North Africans; Pasiegos; Spaniards Acknowledgments: This work was supported in part by grants from the Ministerio de Educacio ´n (PM95-57, PM96- 21, PM99-0023 and BMC-2001–1299) and Comunidad de Madrid (06/70/97 and 8.3/14/ 98) to A.C and A.-V., and grants from the Ministerio de Sanidad (FIS 97/1119), Fundacio ´n Marque ´s de Valdecilla (FMV 16/99) and Parlamento de Cantabria to F.L.C. Received 13 July 2002, revised 4 October 2002, accepted for publication 17 December 2002 Copyright ß Blackwell Munksgaard 2003 Tissue Antigens. ISSN 0001-2815 Tissue Antigens 2003 61: 384–392 Printed in Denmark. All rights reserved The contribution by P. Sa ´nchez-Velasco and E. Gomez-Casado was equal and the order of authorship is arbitrary. Correspondence and HLA haplotype analyses: the aforementioned populations are more related to each other than to Spaniards and also are genetically close to North Africans. Pasiegos show a slight degree of admixture with central and western Europeans. The origin of these populations is regarded as being either a remnant of the primitive Spanish population (ancient Iberians) or of North African refugees. The first theory is more feasible because there are no records of a prolonged Muslim invasion in these areas during the Middle Ages. 384