GM sheep to be used in fight against cruel disease

By SIMON COLLINS science reporter

New Zealand researchers have won approval to create the world's first flock of sheep that will be genetically modified to get Huntington's disease.

The flock of about 60 ewes and their descendants will give their lives to help scientists learn how the fatal hereditary disease develops.

But the sheep will be bred in Adelaide because the scientists say they cannot afford to get regulatory approval for the project in New Zealand.

Lead researcher Dr Russell Snell said AgResearch was keen to do the work, but getting approval was likely to cost too much and take too long.


Scientists at the state-owned South Australian Research and Development Institute will create the Huntington's flock by injecting a synthetic copy of the genetic mutation that causes Huntington's disease into sheep embryos fertilised artificially in the laboratory.

The embryos will be implanted into sheep's wombs to grow like normal lambs, and if the plan works, a proportion will grow up with the Huntington's gene.

Once a stable sheep line with the gene has been established, the institute will kill one infected sheep and one normal sheep every three months and send their brains to Auckland for analysis.

Auckland University's Professor Richard Faull, a co-leader of the research, said humans with Huntington's did not notice any symptoms until the disease was well advanced, with many brain cells already destroyed.

"We'll do very careful chemical studies to see if there is any evidence [of brain cell death in the sheep] before there are any symptoms," he said.

Professor Faull and Dr Snell said the sheep would not suffer before they were killed.

The animals will not live long enough to develop more advanced symptoms of the disease, such as involuntary jerking and memory loss, because sheep normally live only five to 10 years. Symptoms do not usually start to show in humans until early adulthood, and then take several years to become acute.

"If we are going to develop a therapy, we want to address those changes early on, before the cascade of events occurs later in the disease," Dr Snell said.

The Auckland researchers will make the sheep available to any scientist in the world who wants to test a potential treatment for Huntington's.

The Auckland group itself is among the leaders in the search for a treatment because of a unique "brain bank" of people who died with Huntington's disease whose brains have been donated by their families.

"Having given us the brains of their loved ones, there is an obligation on us to pursue everything," Professor Faull said.

"If anyone has any doubt about whether we should use animal models, just talk to a family. We received a brain ... from a family in Nelson whose loved one died at 44. We had another brain from that same family 11 years ago."


The research is financed by $500,000 over eight years from New Zealand Freemasons and just over $500,000 over three years from the US-based Hereditary Disease Foundation.

Freemasons spokesman Terry Meekan said the Masons approached Auckland University after one of their members spoke about the effect of the disease on his family.

HUNTINGTON'S DISEASE

Huntington's is a hereditary disease affecting about 15,000 people in New Zealand.

Every child of a Huntington's sufferer has a 50 per cent chance of inheriting it.

The disease destroys cells in the part of the brain that controls movement.

Symptoms include involuntary jerking, slurred speech and gradual loss of mental ability.