Dolly's four "sisters"
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How have Dolly the Sheep's 'siblings' fared?

The prospect of using cloning to treat humans has been boosted by new evidence that suggests it can be used safely in animals.

Scientists had been worried that cloning could make animals age prematurely, after Dolly the Sheep, the first mammal to be cloned from an adult cell, was diagnosed with osteoarthritis at a young age.

Sangita Myska reports.

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