Risks of Animal Cloning
A cloned animal is born and it makes the international press. Yet when you look behind the headlines you will find that for every success, there are dozens, sometimes hundreds of failed attempts. Animal cloning is still a notoriously difficult and inefficient process.
For example, to produce Snuppy, the world's first cloned dog, more than 1,000 embryos were created, and only three pregnancies were achieved. The success rate with somatic cell transfer is no more than 3% and this could be due to a number of factors including:
1) An incompatibility between enucleated egg and donor DNA
2) Failure of cloned embryo to implant successfully into the womb
3) The egg with the donor DNA may divide incorrectly
Other risks of animal cloning are that cloned animals have been observed to have higher rates of infection and tumour growth, skeletal abnormalities, lung and heart problems, and some like Dolly the sheep die prematurely.
In a famous study in 2002 by Rudolf Jaenisch and his colleagues at the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts mouse genomes were reported to be severely affected by the cloning process. The scientists examined more than 10,000 liver and placental cells of cloned mice and found that up to 4% of the genes functioned abnormally. The problems were not so much with the genes themselves but how they were controlled and expressed.