New Zealand researchers have won approval to create the world's first flock of sheep that will be genetically engineered to get Huntington's disease. The flock of about 60 ewes and their descendants will give their lives to help scientists learn about how the fatal hereditary disease develops, and potentially help to save the lives of the children and grandchildren of humans who now suffer from it. 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 Russell Snell said New Zealand's AgResearch was keen to do the work, but getting approval was likely to cost too much and take too long. "We have to be a little bit pragmatic and do it where we can," he said. Scientists at the state-owned South Australian Research and Development Institute will now 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.

Professor Richard Faull of Auckland University, 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 Paull, who grew up on a Taranaki dairy farm, and Dr Snell, whose father ran the Telford farm training school in Otago, 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 research is funded 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 several years ago after one of their members from Blenheim spoke about the effect of the disease in his family.