Major gene underlying homocysteine levels as candidate gene for IQ?

V.Weiss v-weiss at web.de
Mon Oct 28 07:02:05 EST 2002


Barbaux et. al. (see
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10790895&dopt=Abstract)
investigated the distribution of functional polymorphisms in genes
involved in homocysteine/folate metabolism in children with high IQ
and in children with average IQ. No differences in the frequencies of
genetic variants in the methionine synthase or
methylenetetrahydrofolate reductase genes were found. However, the
cystathionine beta-synthase (CBS) 844ins68 allele was significantly
underrepresented in children with high IQ. But, in the meantime, there
have been already discovered a number of additional non-pathogenic
common polymorphisms of CBS (see
http://www.uchsc.edu/sm/cbs/cbsdata/polymorphism.htm)of which a
possible relationship with IQ should be investigated.  In this context
it is quite interesting that in the paper by Yee et al. ("Major gene
evidence after MTHFR-segregation analysis of serum homocysteine in
families ... ",published in Human Genetics 111 (2002) 128-135, see
http://link.springer.de/link/service/journals/00439/tocs/t2111002.htm)on
page 133 a quantitative distribution of homocysteine levels is shown
with nearly exactly such gene frequencies of a major gene
polymorphism, as the frontpage of the book “Die IQ-Falle”
claimes for the major gene of IQ (see
http://www.volkmar-weiss.de/publ-e.html). The most probably
biochemical cause of Yee’s genotypes of homocysteine levels is
the effect of a common polymorphism of CBS (see
http://www.volkmar-weiss.de/homocysteine.html ,
http://www.volkmar-weiss.de/majgenes.html  and
http://www.volkmar-weiss.de/intellig.html . The later papers are
mirrored on an server of Stanford University by
http://www.slac.stanford.edu/~terryh/ adding step by step
http://www.slac.stanford.edu/~terryh/01Books/010Human-Paradigm/390Intelligence-IQ/050General-IQ.html
and http://www.slac.stanford.edu/~terryh/01Books/010Human-Paradigm/390Intelligence-IQ/040IQ-and-Gene.html).
The reigning doctrine believes that general cognitive ability and IQ,
respectively, have a  background of some hundred polygenes, all with
very small contributions. Contrary to this, Weiss is convinced that
general intelligence has a major gene locus, contributing up to 40% of
the variance, two or three minor loci (dyslexia, … ) with few
percent and, of course, a large number of loci with very small
contributions, too.



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