A nervous system disorder in sheep might someday help people who suffer from Huntington's disease.
According to one South Dakota producer, if research is approved, there could be a need for an additional 75,000 ewes each year to provide a potential treatment used to treat patients with the disease.
Larry and Sue Holler of White spoke at the Dakota Lamb Growers Cooperative annual meeting earlier this month in Aberdeen. Larry Holler is a veterinarian. The couple founded Glycoscience Research Inc. more than two decades ago and maintain a flock of sheep that has a genetic trait that could eventually help combat not only Huntington's but Parkinson's disease, too.
The Hollers' 400 sheep carry the what's called the GM1 gangliosidosis, an inherited disease that progressively destroys nerve cells in the brain and spinal cord. And members of the co-op are considering an increase in production so that when clinical trials begin, lambs will be available to produce the material that could be a medical advance.
The Hollers said there are about 30,000 clinical Huntington's disease patients in the United States and an additional 75,000 people who carry the dominant genetic defect in the Huntington's protein gene. Using current estimates, one lamb could treat one Huntington's disease patient for one year.
After a Food and Drug Administration pre-investigative meeting in January, a clinical trial could be in going by late 2015, according to the Hollers. If that goes as expected, sheep producers will face the challenge of raising enough lambs fast enough to treat Huntington's disease patients.
Researching the gene
While the term GM1 ganglioside is unfamiliar to most, it is critically important to people who suffer from Huntington's disease.
Families affected by Huntington's formed a nonprofit organization called The Shepherd's Gift to support development of GM1 for treatment. They hope to raise money to support sheep producers in their efforts to bring GM1 to the clinic.
The genetics have been shared with other producers in South Dakota, North Dakota, Iowa and Minnesota, adding 4,000 ewes to the project. The Hollers have worked with researchers to get the GM1 material into clinical trials for Huntington's disease in conjunction with Dr. Steve Hersch, a clinical doctor and researcher from Harvard Massachusetts General Hospital.
Holler estimates that it could cost a couple of million dollars to get the substance to clinical trials. Hersch is concentrating on the funding and the trials while the Hollers are focused on raising sheep. They anticipate the FDA will be closely monitoring the progress.
The researchers hope the upcoming review by the FDA will be favorable, and they can quickly prepare for the clinical trial.
“It will be challenging to produce enough lambs to meet the need fast enough for those suffering with HD. That's why it's so important for us that these producers have taken the first steps to start growing the flock that will be needed in the future,” Larry Holler said. “Through selective breeding, we've introduced a lot of different genetics, creating carrier sheep that should work in anyone's flock.”
Huntington's disease is a hereditary, degenerative that diminishes the ability of those who have it to walk, talk and reason. There is no cure for it.
Raise more sheep
Producers at the Aberdeen meeting were excited about the prospect of raising more animals.
Jeff Petersen has purchased nine of the carrier rams for his operation near Oakes, N.D.
“I think it's a unique opportunity to help provide profitability,” Petersen said. “And the project has a great human aspect to help a community of people seeking to find a cure for their disease. It will be great if by raising lambs we can extend and improve the quality of their lives.”
Petersen believes this program will spur growth in the sheep industry. If the program works as expected, producers could receive $500 for a 60-day affected lamb. The current price for lambs is $1.50 to $1.60 per pound for a 140 lb. market lamb, resulting in a price of $210 to $224 per animal.
He said sheep adapt well, and there is a lot of crop residue that could be used for feed. He also pointed out that feed is readily available from ethanol and sugar beet plants.
There was some sheep swapping taking place as the Hollers delivered two rams to Pete Kronberg from Forbes, N.D. Kronberg and his brother Thomas work with their dad, Keith, raising 860 sheep. The family has raised sheep for a long time.
The Hollers said there are facilities to process all lambs currently produced; however, it is anticipated that a dedicated facility would be required to collect tissues from the large numbers of animals that would be needed for pharmaceutical production.
“This project is about value-added sheep production and the chance to help those who suffer with an untreatable disease. We believe these special lambs were created for this very purpose,” Larry Holler said. “Raising (affected) lambs is not really any different than raising other lambs.”
He estimates they will need 75,000 carrier ewes in the network to eventually produce enough GM1 for Huntington's disease patients. Then there is Parkinson's disease. GM1 has already been shown to put Parkinson's disease into a remission state in human clinical trials, and with over 1 million Parkinson's patients, the demand for GM1 sheep could be significant.\
Parkinson's disease is a progressive nervous system disease that leads to tremors, muscular rigidity and imprecise movement.
“The technology is in place. The safety of GM1 has been established. The only thing holding up the process of bringing GM1 to the HD community is money,” Holler said. “We hope to send out every carrier ram that we can raise into the system. We can't do it fast enough for those affected by Huntington's disease.”
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What is GM1?
A naturally occurring molecule, GM1 ganglioside accumulates in the tissues of an affected lamb due to a single gene mutation in the enzyme that would normally break down the GM1 molecule.
Tissues are collected from affected lambs at slaughter, and the GM1 ganglioside is extracted in the laboratory.
Now, the GM1 can't be synthesized, and GM1 sheep are the only verified source to economically produce GM1 ganglioside.
Carrier ewes are clinically normal and are raised in normal sheep production systems. At birth, affected lambs act normally and show no clinical differences from flock-mates. However, the affected lambs will eventually succumb to the gradual accumulation of GM1 ganglioside. They are slaughtered when they are 5 or 6 months old, and the needed tissues are collected and stored. A genetic test is used at birth to identify affected, carrier and normal lambs.