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Times of India
16 April 2010
London, UK

Experts Find Way To Prevent Genetic Flaws By Swapping DNA Between Eggs From 2 Women
‘3-parent’ babies to be free from rare diseases
British scientists have mastered a controversial technique using cloning technology to prevent some incurable inherited diseases by swapping DNA between two fertilized human eggs.

Lead researcher Doug Turnbull of Newcastle University said on Wednesday he hoped the first babies free from so–called mitochondrial diseases would be born within three years.

But applying the technique in the clinic, to help women at risk of passing on the disorders, will require a change in British law that currently bans reproduction from such manipulated embryos, which would end up having three biological parents.

Around one in 6,500 children are born with serious diseases caused by malfunctioning mitochondrial DNA, leading to a range of conditions that can include fatal heart problems, liver failure, brain disorders, blindness and muscular weakness.

The Newcastle team’s technique effectively replaces mitochondria, which act as tiny energy–generating batteries inside cells, so a baby doesn’t inherit faults from its mother. Mitochondria are only passed down the maternal line. “What we’ve done is like changing the battery on a laptop. The energy supply now works properly, but none of the information on the hard drive has been changed,” Turnbull said.

“A child born using this method would have correctly functioning mitochondria, but in every other respect would get all their genetic information from their father and mother.”

The experts used a variation of the same technique used to make Dolly the cloned sheep in 1996.

Within a day of uniting egg and sperm using in vitro fertilization, nuclear DNA is removed from the embryo and implanted into a donor egg, whose own nucleus has been removed and discarded.

The resulting embryo inherits nuclear DNA, or genes, from both its parents but mitochondrial DNA from a second “mother” who donated the healthy egg. In humans, about 37 genes are found in the mitochondria – the rest of the more than 20,000 known genes are in the DNA found in the nucleus.

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