Gene could give clue to cloning failures

Researchers believe they have discovered a crucial gene that explains why so few attempts to clone embryos are successful.

Examining cloned mouse embryos, the researchers discovered that only a small number of embryos properly expressed the gene called Oct4, which is crucial for normal development (Genes and Development 2002;16:1189-93)

“Basically, it's a miracle that cloning actually works,” said the study's lead author, Dr K John McLaughlin of the University of Pennsylvania.

“In the mouse, after just four days of development, we can say that 99% of all clones are doomed to fail,” said Dr McLaughlin. …