The free journal PLoS Genetics has a new article which shows that Mediterranean Europeans can be fairly well distinguished from other Europeans using a genome-wide panel comprising 5,700+ SNP markers.
PLoS Genetics (early online release)
European Population Substructure: Clustering of Northern and Southern Populations
Michael F Seldin et al.
The development of methodologies for defining population genetic structure has provided the ability to identify the major ethnic contributions in individual subjects in diverse populations. Using a genome-wide SNP panel we observe population structure in a diverse group of Europeans and European Americans. Under a variety of conditions and tests there is a consistent and reproducible distinction between "northern" and "southern" European population groups: most individual subjects with southern European ancestry (Italian, Spanish, Portuguese, and Greek) have >85% membership in the "south" population; and most northern, western, eastern and central Europeans have >90% in the "north" population group. Ashkenazi Jewish as well as Sephardic Jewish origin also showed >85% membership in the "south" population consistent with a later Mediterranean origin of these ethnic groups. Based on this work, we have developed a core set of informative SNP markers that can control for this partition in European population structure in a variety of clinical and genetic studies.