Scientists Try New Technique to Modify DNA in Human Eggs

A new gene-editing technique has been used to research whether the DNA contained in human egg cells can be modified to help eliminate hereditary diseases, a plan some scientists want to stop because of beliefs that such procedures are risky and ethically unacceptable.

Researchers at Harvard Medical School used the recently developed Crispr technique on ovarian tissue taken from a woman with inherited ovarian cancer to determine if the procedure could produce embryos that were free of the disease, The Independent reports

Such techniques, which involve editing human chromosomes from either eggs or sperm in order to create embryos that can be used in in-vitro fertilization procedures, are illegal in Britain and many other countries, reports The Independent, because of the possibility of creating "designer babies."

But many scientists believe such procedures can  help couples have children who are free of inherited diseases and prevent them from passing on the genes to future generations.

Many researchers worldwide have been working on the Crispr technique, called "germ-line" gene therapy, with the "germ" cells, or sperm and eggs, being what passes on the genetic line.

At Harvard, the scientists also worked with human tissue to correct the defective BRCA1 gene, which is involved in inherited breast and ovarian cancer.

The Harvard study has not yet been published. The work was carried out last year by researcher Luhan Yang, working in the lab of Harvard geneticist George Church.

Church told The Independent that the work was purely experimental and there was no intention of fertilizing any of the eggs or implanting them.

"Almost all post-docs in a cutting-edge lab like mine like to explore what is possible," Church said. "The experiments were not in human beings. They were in cells in culture. Our lab works on human cells of all sorts, and it is quite likely that at some point she [Dr Yang] has worked on human cells that could be the lineage of oocytes. I’m not sure they were proven to be functional oocytes."

Church termed the experiments as "very basic science" and there is a big difference between doing experiments and actually putting the eggs into a human being.

The Crispr (pronounced "crisper") technique has already been used to correct hereditary disease in lab animals and on human genetic defects found in non "germ" cells, and the precision of the technique has led researchers to also consider it for human germ-line therapy.

But Church also believes that there should be more controls on who uses the technique for germ-line therapy in embryos intended to be implanted.

And leading academics, including geneticist Fyodor Urnov, one of the pioneers of gene editing, said there is danger in moving too fast.

"Genome editing in human embryos using current technologies could have unpredictable effects on future generations," Urnov and other experts wrote in the journal "Nature." "This makes it dangerous and ethically unacceptable."

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