Jeff Carroll had been married for six months when he and his wife decided not to have children. Carroll, 25 years old and a former corporal in the US Army, had just found out that he had the mutation that causes Huntington’s disease, a genetic disorder that ravages the brain and nervous system and invariably ends in an early death.
Public surveys often find support for heritable genome editing — if it is shown to be safe and used to treat genetic diseases. A UK survey conducted by the Royal Society found that 83% of participants were in favour of editing the germ line to treat incurable disease. But many drew the line at editing for ‘enhancement’: 60%, for example, were opposed to the idea of using heritable gene editing to improve intelligence.
Many scientists and ethicists make a similar distinction, between modifying the genome to enhance athletic ability, for example, or to change eye colour, versus treating or preventing disease. And even then, there is debate about which diseases might warrant such an approach. Fatal conditions with a strong, clear-cut genetic contribution — such as Huntington’s disease, which is almost inevitable when the mutation is present — are the most common examples given. But when it comes to editing a gene such as PCSK9 to prevent high cholesterol and potentially stave off heart disease, things are decidedly more grey, says Feng. Ultimately, Porteus hopes to see a registry of conditions that have been evaluated by specialists and deemed worthy of intervention with heritable gene editing, much as the United Kingdom now maintains for PGD.