A scientist has been making her case to be the first in the UK to be allowed to genetically modify human embryos.
Dr Kathy Niakan said the experiments would provide a deeper understanding of the earliest moments of human life and could reduce miscarriages.
The regulator, the Human Fertilisation and Embryology Authority (HFEA), will consider her application on Thursday.
If Dr Niakan is given approval then the first such embryos could be created by the summer.
Every person has gone through a remarkable transformation from a single fertilised egg into a fully fledged human being made of trillions of precisely organised cells.
Exactly how this takes place is a mystery.
Dr Niakan, who has spent a decade researching human development, is trying to understand the first seven days.
During this time we go from a fertilised egg to a structure called a blastocyst, containing 200-300 cells.
But even at this early blastocyst stage, some cells have been organised to perform specific roles – some go on to form the placenta, others the yolk sac and others ultimately us.
During this period, parts of our DNA are highly active.
It is likely these genes are guiding our early development but it is unclear exactly what they are doing or what goes wrong in miscarriage.
Dr Niakan, from the Francis Crick Institute, said: “We would really like to understand the genes needed for a human embryo to develop successfully into a healthy baby.
“The reason why it is so important is because miscarriages and infertility are extremely common, but they’re not very well understood.” Of 100 fertilised eggs, fewer than 50 reach the blastocyst stage, 25 implant into the womb and only 13 develop beyond three months.
She says that understanding what is supposed to happen and what can go wrong could improve IVF. “We believe that this research could really lead to improvements in infertility treatment and ultimately provide us with a deeper understanding of the earliest stages of human life.”
