Northern vs. Southern Europeans

Here, the authors type over 5000 SNPs in about 1000 Europeans and European Americans, use STRUCTURE, and find clustering that corresponds to Northern vs. Southern Europeans. Among other findings, the Finns clustered very strongly, Ashkenazi and Sephardic Jews clustered with the Southern Europeans.
Disease differences among Europeans according to authors: type 1 diabetes, Crohn' s disease, multiple sclerosis. (but also celiac disease, malaria, cystic fibrosis??)

European Population Substructure: Clustering of Northern and Southern Populations

Michael F. Seldin, Russell Shigeta, Pablo Villoslada, Carlo Selmi, Jaakko Tuomilehto, Gabriel Silva, John W. Belmont, Lars Klareskog, Peter K. Gregersen

PLoS Genetics: Volume 2 | Issue 9 | SEPTEMBER 2006

Synopsis: Two unrelated persons in the human population have hundreds of thousands of base pair differences between them in DNA sequence. Previous studies have shown that a small proportion of these sequence differences correlate with a person's continental ancestry: broadly, Asia, Africa Oceana, America, or continental Europe. In the current study, DNA differences within a particular continental group, Europe, were examined. Overall, the analysis of sequence variation allowed the authors to distinguish individuals with northern European ancestry (Swedish, English, Irish, German, and Ukrainian) from individuals with southern European ancestry (Italian, Spanish, Portuguese, and Greek). Interestingly, Ashkenazi Jewish individuals tend to group together with individuals from southern European countries. This study is important because it provides a method of taking into account these differences when searching for genetic variations that are associated with particular human traits, such as disease susceptibility, response to drug treatment, or side effects from therapy. Specifically, these methods may allow scientists to uncover disease-associated genetic variations that might be hidden unless differences related to European ancestry are considered.