highly significantp = 5 × 10 −7
In the two large UK control samples, for example, there was a highly significant ( p = 5 × 10 −7 , using an exact implementation of the Cochran–Armitage trend test) difference in allele frequencies between UK1 (recruited exclusively in Scotland) and UK2 (recruited throughout the UK), which made us consider the possibility that this variant showed variation in allele frequency along the south–north cline as previously described in the WTCCC study and others [ 16 , 23 – 26 ].