title: New population and phylogenetic features of the internal variation within mitochondrial DNA macro-haplogroup R0.
abstract: BACKGROUND
  R0 embraces the most common mitochondrial DNA (mtDNA) lineage in West Eurasia, namely, haplogroup H (approximately 40%). R0 sub-lineages are badly defined in the control region and therefore, the analysis of diagnostic coding region polymorphisms is needed in order to gain resolution in population and medical studies.
  
  
  RESULTS
  We sequenced the first hypervariable segment (HVS-I) of 518 individuals from different North Iberian regions. The mtDNAs belonging to R0 (approximately 57%) were further genotyped for a set of 71 coding region SNPs characterizing major and minor branches of R0. We found that the North Iberian Peninsula shows moderate levels of population stratification; for instance, haplogroup V reaches the highest frequency in Cantabria (north-central Iberia), but lower in Galicia (northwest Iberia) and Catalonia (northeast Iberia). When compared to other European and Middle East populations, haplogroups H1, H3 and H5a show frequency peaks in the Franco-Cantabrian region, declining from West towards the East and South Europe. In addition, we have characterized, by way of complete genome sequencing, a new autochthonous clade of haplogroup H in the Basque country, named H2a5. Its coalescence age, 15.6+/-8 thousand years ago (kya), dates to the period immediately after the Last Glacial Maximum (LGM).
  
  
  CONCLUSIONS
  In contrast to other H lineages that experienced re-expansion outside the Franco-Cantabrian refuge after the LGM (e.g. H1 and H3), H2a5 most likely remained confined to this area till present days.
authors.affiliation: Unidade de Xenética, Instituto de Medicina Legal and Departamento de Anatomía Patolóxica y Ciencias Forenses, Facultade de Medicina, Universidade de Santiago de Compostela, Galicia, Spain.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Alvarez-Iglesias
authors.forename: Ana
authors.initials: A
authors.lastname: Mosquera-Miguel
authors.forename: Maria
authors.initials: M
authors.lastname: Cerezo
authors.forename: Beatriz
authors.initials: B
authors.lastname: Quintáns
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Zarrabeitia
authors.forename: Ivon
authors.initials: I
authors.lastname: Cuscó
authors.forename: Maria Victoria
authors.initials: MV
authors.lastname: Lareu
authors.forename: Oscar
authors.initials: O
authors.lastname: García
authors.forename: Luis
authors.initials: L
authors.lastname: Pérez-Jurado
authors.forename: Angel
authors.initials: A
authors.lastname: Carracedo
authors.forename: Antonio
authors.initials: A
authors.lastname: Salas