Reader Comments
Post a new comment on this article
Post Your Discussion Comment
Please follow our guidelines for comments and review our competing interests policy. Comments that do not conform to our guidelines will be promptly removed and the user account disabled. The following must be avoided:
- Remarks that could be interpreted as allegations of misconduct
- Unsupported assertions or statements
- Inflammatory or insulting language
Thank You!
Thank you for taking the time to flag this posting; we review flagged postings on a regular basis.
closeWhich alleles are associated? Chimp-like allele is higher functioning?
Posted by fryera on 22 Oct 2009 at 22:02 GMT
In papers of this type (where SNP genotypes are being associated with phenotypic traits) I feel it should be mandatory that the authors state explicitly WHICH of the two alleles of each SNP is being claimed to be associated with the linked phenotype. It is rather frustrating that one can search in vain through the whole paper and the supplemental info document and still not be able to find any clear information on exactly which SNP allele genotypes are being claimed to be associated with the cognitive phenotypes.
Only for the two of their SNPs (rs10507435 and rs943220) did LeHellard et al even provide a hint as to which allele is associated with cognitive phenotypes. In these two instances they indicate that the G allele of rs10507435, and the C allele of rs943220, are each "associated with reduced verbal memory performance". However both of these alleles are actually the derived alleles! Therefore LeHellard et al are in effect postulating that the evolved human-derived alleles encode for REDUCED cognitive ability and that the ancestral alleles (shared by the primate precursor to hominids and chimps--who presumably would be expected to manifest lower cognitive ability) encode for HIGHER cognitive ability.
This of course does not make any intuitive sense and is one reason to suspect that the genotype-phenotype association claimed by LeHellard et al will turn out to be false (i.e. mere random variation). Another reason to be dubious about these results is that there is lack of consistent genotype-phenotype correlation across the three cohorts for many of the SNPs.
Also there is little or no evidence that random SNPs located in the middle of huge introns actually have any functional importance. If any of these SNPs were in the 5' promoter region of the DCLK1 gene, or if they were nonsynonymous coding SNPs, or if they were in the 3'UTR (which could alter microRNA binding sites) THEN perhaps these claims could be regarded as more plausible.
I suspect that there is at least a 95% chance that the claims of this paper (like the claims present in more than 95% of other similar papers that have claimed "significant associations" of particular SNPs with human mental traits or mental diseases) will eventually turn out to be unfounded.