Why are Border Collies so smart?

In a recent documentary by Nova Science Now: how smart are animals? The report stated that researchers studying dog genomes have found a gene that may be responsible for their higher level of intelligence when compared to other dog breeds.
It's called...CTNND2. In humans, this gene is important for normal cognitive development. The Border Collie genome shows selective breeding for this gene. However after an extensive search through the literature, I can find no references to this claim. I would be interested to hear if anyone is researching this field.