Sunday, November 10, 2013

In My Genes

The genes are there, per my report from   What they might mean and the firmness of the finding rates from one star to four stars.  The findings are actually all from people of European ancestry.  Whether they might be different for people of South Asian ancestry is not known.

The researchers found that being breastfed raised a person’s IQ an average of six to seven points, but only among those who had at least one C at rs174575. Among those with a G at both copies of rs174575, breastfeeding appeared to have no effect on intelligence. This result was found in two independent groups, one composed of 1,848 British children and the other of 858 children of European ancestry from New Zealand. The effect associated with this SNP was larger than the one described below for rs1535, which is included for customers who do not have data from rs174575.

I am CC.

Nonword reading refers to the ability to read combinations of letter-sounds that don't correspond to actual words. In this study, researchers examined tests of reading ability in young adult twins and siblings of European descent from nearly 800 families. They found that each C at rs11857829 near the DYX1C1 gene (equivalent to rs17819126 reported in the study) was associated with a slightly higher score for nonword reading. The DYX1C1 gene has been previously implicated in developmental dyslexia.

I am TT.

A study of Dutch families found that rs363050 is associated with "performance IQ" (i.e. non-verbal IQ). Each A at rs363050 increased subjects' performance IQ by an average of three points compared to those with no copies. The authors estimated that rs363050 accounts for 3.4% of the variation in performance IQ between people.

I am AG.

In this study, the authors asked people to read or listen to lists of words and then recall them later. People with at least one T at rs17070145 performed about 20% better than those with a C at both copies of the SNP five minutes and 24 hours after seeing or hearing the lists. The SNP lies within a gene called KIBRA that is thought to be involved with episodic memory, which involves the recall of events rather than information. (Note: the KIBRA gene is listed in the Genome Explorer as WWC1.)

 I am CC.

In this study, 26 healthy German subjects took a test that assessed their ability to prefer "correct" choices and avoid "incorrect" ones. The authors also genotyped the subjects at the SNP rs1800497, which is thought to affect a gene involved in dopamine signaling. People with the GG genotype learned to avoid choices associated with negative feedback relatively easily, while people with the AG or AA genotypes did not learn as well to avoid these choices; in other words, they did not learn from their mistakes. (Note: Rs1800497 is commonly referred to in the scientific literature as the DRD2 TaqIA polymorphism. The A version of rs1800497 is equivalent to the A1 allele of DRD2 TaqIA, while the G version of the SNP corresponds to the A2 allele.)

I am AA.

The first marker is intriguing.   After learning about it, one can ask questions - were the other markers checked against breast-fed/non-breast-fed?  And any of a myriad of other possible relevant factors that might affect the expression of genes.

The abstract of the paper referred to is below, and the paper is available for free.  Noteworthy is this highlighted below - that they have only found a correlation, not a cause.  So "Project Einstein" or other such projects may find genes that correlate with IQ and still will be far from the mark.
The genetic moderation of breastfeeding effects on IQ is unlikely to be directly caused by the analyzed SNP, and the molecular mechanism by which rs174575 may influence cognitive development is not known.
Proc Natl Acad Sci U S A. 2007 Nov 20;104(47):18860-5. Epub 2007 Nov 5.

Moderation of breastfeeding effects on the IQ by genetic variation in fatty acid metabolism.


Medical Research Council Social, Genetic, and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, London SE5 8AF, England.


Children's intellectual development is influenced by both genetic inheritance and environmental experiences. Breastfeeding is one of the earliest such postnatal experiences. Breastfed children attain higher IQ scores than children not fed breast milk, presumably because of the fatty acids uniquely available in breast milk. Here we show that the association between breastfeeding and IQ is moderated by a genetic variant in FADS2, a gene involved in the genetic control of fatty acid pathways. We confirmed this gene-environment interaction in two birth cohorts, and we ruled out alternative explanations of the finding involving gene-exposure correlation, intrauterine growth, social class, and maternal cognitive ability, as well as maternal genotype effects on breastfeeding and breast milk. The finding shows that environmental exposures can be used to uncover novel candidate genes in complex phenotypes. It also shows that genes may work via the environment to shape the IQ, helping to close the nature versus nurture debate.