What is pro-nuclear transfer (PNT)?
A pro-nucleus is a small round structure which develops in an embryo following fertilisation. Normally an embryo contains two pronuclei, one from the egg and one from the sperm. They contain the nuclear DNA of the mother and father which determines the resulting child’s genetic traits.
Pro-nuclear transfer (PNT) involves transferring the pronuclei from an embryo with unhealthy mitochondria into a donor embryo which contains healthy mitochondria but has had its pronuclei removed. The donor embryo would either be created especially for this purpose, from donor eggs and donor sperm, or could be donated from a couple undergoing IVF.
This new embryo contains nuclear DNA from the intended father and mother and healthy mitochondrial DNA from the donor embryo.
The donor embryo’s nuclear material will be destroyed following the procedure.
Step by step: how PNT works
PNT involves genetically modifying an embryo, which is not currently permitted in treatment in the UK. Explore the ethical issues associated with this medical technique: