Scientists want to be able to genetically engineer humans so that they don't get diseases.
That is the conclusion of a new report from two of the world's most elite scientific institutions, which calls for people to be allowed to make modifications to inherited human DNA so that diseases are edited out or treatments are edited in.
Such controversial changes could allow scientists to stop diseases from being passed on to future generations.
The report is a landmark because it in effect amounts to an official sanctioning – by the National Academy of Sciences and National Academy of Medicine – of medical research that looks to edit, remove or add DNA in human eggs cells, sperm or embryos.
But opponents have argued that editing for specific problems could begin a trend for making other changes, like adding selected physical features or optimising children so that they are strong or fast.
Gene editing, which effectively allows the precise "cutting and pasting" of DNA, is already used in basic research and clinical studies that involve non-heritable "somatic" cells.
Now the two elite organisations have ruled that gene editing of the human "germline" - inherited DNA - should not be seen as a red line in medical research.
Future use of germline gene editing to treat or prevent disease and disability is a "realistic possibility that deserves serious consideration", the report says.
However, the two academies point out that the technology is not yet safe enough to justify testing it on the inherited DNA of human patients.
They add that gene editing for enhancement should not be allowed "at this time" - but do not rule it out completely.
A broad public debate should be held before permitting clinical trials, even those involving non-inherited DNA, for any purpose other than treating or preventing disease, the report says.
Professor Alta Charo, from the University of Wisconsin-Madison in the US, who co-chaired a study committee appointed by the academies to investigate the wider implications of gene editing, said: "Human genome editing holds tremendous promise for understanding, treating or preventing many devastating genetic diseases, and for improving treatment of many other illnesses.
"However, genome editing to enhance traits or abilities beyond ordinary health raises concerns about whether the benefits can outweigh the risks, and about fairness if available only to some people."
Currently research that involves modifying inherited genes in human embryos is not allowed in the US, and a number of other countries have signed an international convention that prohibits it.
Altering germline DNA is also banned in the UK, with one important exception. Parliament has ruled that inherited DNA in the mitochondria - tiny power plants in cells that supply energy - can be replaced if they are defective and the cause of devastating diseases that are passed down from mothers to their children.
Mitochondrial DNA makes up only about 0.1% of all the inherited genetic material in a human cell and does not affect key characteristics such as hair and eye colour or personality.
