Researchers at the University of Pennsylvania, US, have reported that they have discovered that a single gene, 'essential' to embryo development, is lacking in many cloned embryos. The research is published in the journal Genes and Development.
The gene, known as Oct4, must be expressed at certain levels and at the right time in order for embryo development to proceed normally. When looking at cloned mouse embryos, the scientists found that the right quantity of the Oct4 gene was present in only ten per cent of them.
Team leader Hans Scholer believes that the discovery adds weight to arguments against reproductive cloning, saying that cloning humans 'is not something we should try to pursue, because if you're having a problem at the very beginning, we know that this is a problem that can be maintained through the later stages'. But he added that the discovery should have no adverse effects on therapeutic cloning, as it was found that 'the small number of clones that did adequately express Oct4 were capable of forming embryonic stem cell lines'.
Robert Lanza, the director of Advanced Cell Technology, the US biotechnology company that last year announced it had created six-celled cloned human embryos, said that 'we need to investigate this before we can even think about applying this to humans'.
Sources and References
Single gene failure 'explains cloning deaths'
Single gene may determine cloning success, scientists report