Thank you, Carl Shulman, for correcting my misinformation. It's difficult for one to know which references are reliable, when one is not in the field.

@Carl Shulman: The largest hypothesized effects of the disease alleles would be only a small fraction of the Ashkenazim advantage: they just aren't frequent enough.

Dr. Bostrom cites this paper (so I considered it might be reliable) in his treatise on cognitive enhancement: "Natural History of Ashkenazi Intelligence" by Gregory Cochran, Jason Hardy, Henry Harpending. Speaking of the incidence of of the Ashkenazim mutations, they state: "the probability of having at least one allele from these disorders is 59%.". As I understand it, these disorders are exceedingly rare in non-Ashkenazim. Are these authors simply incorrect, or did you mean that a 59% incidence just isn't frequent enough? That incidence is very close to the intelligence distribution I read between mutated and non-mutated Ashkenazim. Coincidence? Or already discredited?