BioWorld International Correspondent

LONDON - The world's most famous sheep and first clone, Dolly, died Friday at age 6. She was put down after vets at the Roslin Institute in Edinburgh, Scotland, where she was born and lived, found she was suffering from a progressive lung disease.

Dolly caused a storm of global controversy when her birth was announced in February 1997. She was apparently fit and healthy, and produced six healthy offspring.

However, just over a year ago, on Jan. 4, 2001, the Roslin Institute announced Dolly was suffering from arthritis in her left hind leg. That raised the question that because she was cloned from adult cells Dolly was prematurely aging. Ian Wilmut, head of the team that cloned Dolly, said it was not possible to know if the arthritis was in any way the result of her being a clone.

PPL Therapeutics plc in Edinburgh, which is using the cloning technology to generate transgenic animals that produce therapeutic proteins in their milk, said there were no commercial implications of Dolly's arthritis for its programs. While not wanting to breed animals with health problems, the company is not interested in the founder animals, but in using them to create offspring with the desired genetic profiles.

Roslin Institute and PPL Therapeutics officials could not be reached for comment Friday evening, when the news was released.