Genetic heterogeneity between the six different European control cohorts.

Genetic heterogeneity between the six different European control cohorts. Allele frequencies were compared between all control populations using a chi squared test. The percentage of comparisons where a statistically significant result was seen (P<0.05) is shown in the table. A low percentage indicates that there were few markers at which allele frequencies differed between 2 populations of interest suggesting that there is little genetic heterogeneity between those two populations. A high percentage indicates that allele frequencies between two populations differed significantly at multiple markers, suggesting significant genetic heterogeneity between those two populations. Between the German and Swedish control cohorts, allele frequencies did not differ significantly at a single marker, suggesting that these populations are relatively genetically similar. By contrast, the UK and Italian control cohorts differed significantly at 73% of markers tested, suggesting significant genetic heterogeneity between these two cohorts.