La Follette School Professor Jason Fletcher discussed the social genomics revolution with co-author Dalton Conley during a Freakonomics’ podcast June 14. The episode – Evolution, Accelerated – focused on the advances in genetics and their societal implications.
“Just two decades ago, it cost a billion dollars to sequence a single genome,” said Fletcher, whose book The Genome Factor was published earlier this year. “Now you and I could spit in a cup, send it to one of the popular sequencing outfits and for $100 or for $150 we can get millions of answers to the question, ‘What does our DNA look like’?”
When the Human Genome Project (HGP) said in 2000 that it completed a map of the entire human genome, Conley and Fletcher said, the hope was that scientists would find single, identifiable genes that controlled individual diseases, personal attributes such as height or intelligence, and other human conditions.
That was an exception rather than a rule, Fletcher told Stephen J. Dubner, the author and host of Freakonomics. “Most of life’s important outcomes are not one gene and one disease,” he said. “They’re more like hundreds of thousands of genes all with really tiny effects, if you can even find them.”
One popular genetic testing and analysis company has more than a million DNA samples from mainly U.S. citizens in its database. Social and genomic scientists like Fletcher and Conley are using this type of data to try to understand Alzheimer’s disease, educational attainment, and other outcomes.
“We finally have big data sets with lots of genetic markers across the entire set of chromosomes,” Conley, a sociology professor at Princeton University, told Dubner. “We’re now actually making robust discoveries that are withstanding replication and seem pretty solid. That’s the start of the revolution. But, warning: it’s still early days.”
This wealth of data and gene-editing tools such as CRISPR (clustered regularly interspaced short palindromic repeats) are exciting for single-gene diseases such as cystic fibrosis and sickle-cell disease. However, heart disease, body mass index, and other aspects are “the sum total of many little effects all across the chromosomes, and that probably means we’re not going to be doing gene-editing in a thousand different locations in the genome,” Conley said on Freakonomics.
As they do in their book, Fletcher and Conley acknowledged to Dubner their concerns about how this data and technology are used – especially regarding eugenics. University of California-Berkeley Professor Jennifer Doudna, one of the developers of CRISPR, shared that same concern with Dubner.
“I have gone from feeling very uncomfortable with the idea of making changes to human embryos, especially for anything that would be considered not medically essential, to thinking that there may come a time ... when that application is embraced and it’s going to be deployed. For me, the important thing is not to reject it,” she told Dubner. “It’s actually to understand it and really think through the implications.”
Fletcher, Jason M. "Why have tobacco control policies stalled? Using genetic moderation to examine policy impacts." PLoS One 7, no. 12 (2012): e50576.
Fletcher, Jason M., and Dalton Conley. "The challenge of causal inference in gene–environment interaction research: leveraging research designs from the social sciences." American journal of public health 103, no. S1 (2013): S42-S45.
Domingue, Benjamin W., Jason Fletcher, Dalton Conley, and Jason D. Boardman. "Genetic and educational assortative mating among US adults." Proceedings of the National Academy of Sciences 111, no. 22 (2014): 7996-8000.
Conley, Dalton, Thomas Laidley, Daniel W. Belsky, Jason M. Fletcher, Jason D. Boardman, and Benjamin W. Domingue. "Assortative mating and differential fertility by phenotype and genotype across the 20th century." Proceedings of the National Academy of Sciences 113, no. 24 (2016): 6647-6652.
Cook, C. Justin, and Jason M. Fletcher. "Can education rescue genetic liability for cognitive decline?" Social Science & Medicine 127 (2015): 159-170.
Domingue, Benjamin W., Daniel Belsky, Jason Fletcher, Dalton Conley, Jason D. Boardman, and Kathleen Mullan Harris. "Analysis of genetic similarity among friends and schoolmates in the National Longitudinal Study of Adolescent to Adult Health (Add Health)." bioRxiv (2017): 107045.