If most known intelligence related genes could be altered in humans then this would provide a gain of about 10-15 IQ points

Stephen Hsu estimated the impact if we could alter the known intelligence related genes in humans. His estimate is that it would provide an average boost of 10-15 IQ points. It is likely that we have found about 2 to 10% of the intelligence related genes.

Recently published SSGAC study (Nature News) found 74 genome-wide significant hits related to educational attainment, using a discovery sample of ~300k individuals. The UK Biobank sample of ~110k individuals was used as a replication check of the results. If both samples are combined as a discovery sample 162 SNPs are identified at genome-wide significance. These SNPs are likely tagging causal variants that have some effect on cognitive ability.

The SNP hits discovered are common variants — both (+) and (-) versions are found throughout the general population, neither being very rare. This means that a typical individual could carry 80 or so (-) variants. (A more precise estimate can be obtained using the minor allele frequencies of each SNP.)

Imagine that we knew the actual causal genetic variants that are tagged by the discovered SNPs (we don’t, yet), and imagine that we could edit the (-) version to a (+) version (e.g., using CRISPR; note I’m not claiming this is easy to do — it’s a gedanken experiment). How much would the IQ of the edited individual increase? Estimated effect sizes for these SNPs are uncertain, but could be in the range of 1/4 or 1/10 of an IQ point. Multiplying by ~80 gives as a crude estimate of perhaps 10 or 15 IQ points up for grabs, just from the SSGAC hits alone.

Critics of the study point out that only a small fraction of the expected total genetic variance in cognitive ability is accounted for by SSGAC SNPs. But the estimate above shows that the potential biological effect of these SNPs, taken in aggregate, is not small! Indeed, once many more causal variants are known (eventually, perhaps thousands in total), an unimaginably large enhancement of human cognitive ability might be possible.

There has been DNA editing of human embryos

A Swedish researcher is editing the DNA in healthy human embryos. He wants develops efficient editing techniques that will allow him to study the genes involved in early embryonic development. Scientists in Britain are planning to start similar experiments later this year.

Researchers in China have reported editing the genes of human embryos to try to make them resistant to HIV infection. Their paper— which used CRISPR-editing tools in non-viable embryos that were destroyed after three days — is only the second published claim of gene editing in human embryos.

Other countries, such as China and India, are more positive toward enhancement. In China, this may be linked to more generally approving attitudes toward old-fashioned eugenics programs such as selective abortion of fetuses with severe genetic disorders

The biggest barrier to genetic enhancement will be broader statutes banning gene editing. A recent study found bans on germline genetic modification – that is, those that are passed on to descendants – are in effect throughout Europe, Canada and Australia. China, India and other non-Western countries, however, have laxer regulatory regimes – restrictions, if they exist, are often in the form of guidelines rather than statutes.

SOURCES- Infoproc, The Conversation, NPR, Nature

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