Harry Griffin from The Roslin Institute explains the cloning that led to the making of Dolly (2'30")

The Scottish scientists who made Dolly, the first cloned sheep, have taken another big step forward by using human genes in the cloning of two more lambs.

The lambs, named Molly and Polly, have been cloned with a human gene so that their milk will contain a blood-clotting protein that can be extracted for use in treating human hemophilia.

Hello Polly

Scotland's Roslin Institute and its commercial partner, PPL Therapeutics Inc, announced details of the breakthrough in the journal Science.

The journal has named it the 'Breakthrough of the Year.'

Dr Jerome Ravetz of The Genetics Forum: Such advances are amazing (2'40")

The research opens the way to new treatments for cystic fibrosis, emphysema and haemophilia within two or three years and other diseases soon after.

The added human genes make therapeutic products in the sheep's milk so it can be extracted, purified and used to treat patients.

Farmers can benefit from the same technique used to make identical copies of animals that produce exceptional quantities of milk or meat.

Seeing double: Two many sheep

It may be used to produce herds of animals protected against mad cow disease or to genetically engineer pigs so their organs are made perfectly suited for transplanting into humans.

But there are doubts over the use of the same technology in humans. In theory it could be used to genetically duplicate any human.

The same research could be used to add extra genes to human embryos, delete unwanted genes or to allow infertile women to give birth to genetic copies of themselves.

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