Fyodor Urnov: IVF can prevent transmission of a known familial mutation without editing embryo DNA

Fyodor Urnov: IVF can prevent transmission of a known familial mutation without editing embryo DNA

On October 9, gene-editing researcher Fyodor Urnov challenged Origin Genomics’ rationale for editing disease-causing DNA variants in embryos in a post on X. He compared the approach with IVF: if an embryo produced through IVF does not carry the known familial mutation, it can be selected for transfer to the uterus.

In a statement from Origin Genomics, company co-founder Cathy Tie explains the idea as follows: in a developed organ, the editor must reach many cells, whereas an early embryo still has few cells. The company proposes studying this approach to correct mutations that cause severe monogenic diseases, conditions caused by a change in a single gene.

Urnov responds that IVF can often already prevent transmission of a known familial mutation: eggs are fertilized outside the body to produce several embryos, and cells from those embryos are tested. If an embryo has not inherited the disease-causing variant, it is selected for transfer.

A 2014 clinical report describes a case involving inherited prion disease. Of eight embryos produced through IVF, six did not carry the F198S variant; two were transferred, and the patient gave birth to healthy twins.

DNA editing addresses a different starting point: every embryo produced carries the familial variant. In a reply in the same thread, Urnov suggested a possible future application for families in which both parents carry two copies of ApoE4, a DNA variant associated with an increased risk of Alzheimer’s disease. He put the timeframe at “ten years or more.”

The debate concerns the family’s starting point: embryo selection identifies an embryo without the known mutation among those already produced, while editing attempts to correct the mutation within the embryo itself.