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Scientists edit DNA in human embryos to create successful pregnancy

The team used genome-editing techniques to stop a key gene from producing a protein called OCT4, which normally becomes active in the first few days of human embryo development.

Scientists have revealed the key role played by a fertility ‘master gene’ after editing Deoxy Nucleic Acid (DNA)/genetic material in human embryos. Scientists used the controversial CRISPR-Cas9 system to ‘edit’ growing human embryos to see what would occur when a key gene was removed.

The work is published in the journal Nature. They discovered that a protein called OCT4 helped decided whether an embryo grows normally or self-destructs. One of the key applications for the research is to improve IVF success rates.

The team used genome-editing techniques to stop a key gene from producing a protein called OCT4, which normally becomes active in the first few days of human embryo development.

After the egg is fertilised, it divides until at about seven days it forms a ball of around 200 cells called the ‘blastocyst’. The study found that human embryos need OCT4 to correctly form a blastocyst.

The team spent over a year optimising their techniques using mouse embryos and human embryonic stem cells before starting work on human embryos. To inactivate OCT4, they used an editing technique called CRISPR/Cas9 to change the DNA of 41 human embryos. After seven days, embryo development was stopped and the embryos were analysed.

Embryos that had OCT4 inactivated did not develop blastocyst, suggesting they didn’t stand any chance of implanting in the womb. Just 12 per cent of eggs fertilised in the laboratory are viable for implanting in the womb – for reasons that are poorly understood.

But now the genes that lead to the failure are beginning to be uncovered. It is hoped the research will eventually help the one in seven couples who have difficulty having a baby.

Gene editing human embryos is controversial as critics fear it could be used to create ‘designer babies’. The embryos were donated by mothers at an IVF clinic.

This is the first time the technique – known as CRISPR-Cas9 has been used to identify the genes that lead to pregnancies failing.

Teams in China and the United States (US) have used gene editing for different purposes – to remove faulty genes in the embryo that would otherwise result in genetic diseases when a baby is born.

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