Sometimes comments on blogs get lost in the shuffle. I received a comment on my first post on the X-Factor (Large Heart Theory) that I think deserves your attention:
“A fair analysis of the X Factor hypothesis would have to include all potential X passing pedigree positions in which the four sires named above may occur, not just 4 of them. In a male’s 5 gen. pedigree the number of such positions = 7, in females it’s 11.
“It’s a moot point, however, since there is no lack of highly credible genetic evidence debunking this hypothesis which holds that heart size is controlled on the X chromosome. The domestic horse genome was sequenced six years ago, SNP chips developed, and since then the genome of no breed has been scrutinized as closely as the TB. As first proposed ~20 years ago the X factor hypothesis was somewhat simplistic though not altogether implausible and certainly not ‘bizarre.’ But as it turns out the factors controlling heart size aren’t on the X and the hypothesis is false.
“Genomic evidence has already begun to redefine how we study and analyze pedigrees and will no doubt continue to do so. Any ‘transparency’ it might offer must be regarded in full context, i.e. the genome is only one factor in the equation that produces a successful racehorse.”
The important thing about this comment is that it comes from a geneticist who claims (and I do not doubt him in the least) that genetics has already DISPROVED the hypothesis that the large heart gene is carried on the X (female) chromosome. Therefore, my statistics on the subject were all superfluous.
The funny thing is that geneticists and students of pedigrees do not communicate very much or very efficiently (if at all). I feel that my study of the subject was not in vain. After all, it DID elicit the comment above, and the comment above agrees with my analysis that the hypothesis is totally FALSE. You probably would not have heard this comment from a geneticist unless I had raised the subject in the first place.
Incidentally, I did not characterize the theory as “bizarre.” The word “bizarre” was used in another comment on this post.
Lastly, I wholehearted agree with the statement: “The genome is only one factor in the equation that produces a successful racehorse.”