Why a synthetic human genome is still worth building

Ten years ago, when I was a first-year graduate student, my PhD adviser smuggled me into a private meeting at Harvard Medical School in Boston, Massachusetts. I listened in thrall as participants from academia, industry and government debated the ethics, promise and pitfalls of an ambitious project: building a copy of the human genome from scratch using synthetic DNA. A synthetic genome is built by replacing, piece by piece, a cell’s natural genome with DNA made in the laboratory. The artificial sequences can be copies of their natural counterparts or designed to give the cell properties that aren’t found in nature. AI tools can design genomes. Will they upend how life evolves? When the synthetic human genome project was made public in June 2016 , it had two main goals. First, to slash the cost of engineering large genomes by 1,000-fold within a decade. And, second, to produce a cell line with an ‘ultrasafe’ synthetic genome that was engineered to, for instance, make the cells less prone to viral infection. But efforts never really got off the ground. At the time, the technological landscape was not ready to support the project’s ambitions and, failing to gather enough funding, the project remained a series of pilot research proposals and meetings rather than the centralized programme it set out to be. That no longer needs to be the case. DNA synthesis and assembly methods have improved enough to reliably produce long genomic sequences. …