Andrea Grindeland, DVM

Assistant Professor, Institutional Veterinarian

Education

Assistant Professor

Assistant Professor, TouroCOM Montana

Bachelor of Science, Animal Science, Science option with honors, Montana State University

Doctor of Veterinary Medicine, Mixed Animal Surgery and Medicine, Colorado State University

Huntington’s Disease

What do we know about heredity and Huntington's disease?

Huntington's disease (HD) is an inherited neurological illness causing involuntary movements, severe emotional disturbance and cognitive decline. In the United States alone, about 30,000 people have HD. In addition, 35,000 people exhibit some symptoms and 75,000 people carry the abnormal gene that will cause them to develop the disease. There is no cure for this fatal disease.A single abnormal gene produces HD. In 1993, scientists finally isolated the HD gene on chromosome 4. The gene codes for production of a protein called "huntingtin," whose function is still unknown. But the defective version of the gene has excessive repeats of a three-base sequence, "CAG." In the normal huntingtin gene, this sequence is repeated between 11 and 29 times. In the mutant gene, the repeat occurs over and over again, from 40 times to more than 80. This defect causes the resulting huntingtin protein to be malformed, prone to clumping in the brain and causing the death of nearby nerve cells. Cells of the basal ganglia, a brain area responsible for coordinating movement, and of the cortex, which controls thought, perception and memory, are most often affected. Since the gene that causes HD is dominant, each child of an HD parent has a 50-50 chance of inheriting the HD gene. The child needs only one copy of the gene from either parent to develop the disease.

A person who inherits the HD gene, and survives long enough, will sooner or later develop the disease. If the child does not inherit the defective gene, the child will not get the disease nor pass the gene on to subsequent generations. Symptoms of HD generally appear in mid-life.

Research: Unlocking the Mysteries of Huntington's Disease

The 1993 discovery of the gene, which triggers HD when it malfunctions, jump-started research on this devastating disease. Scientists hope that a multi-faceted approach will lead to a cure.Research is proceeding in many directions:

Basic neurobiology: Scientists are continuing to study the HD gene to better understand how it causes disease.

Imaging: Scientists can observe what the defective gene does to various structures in the brain and how it affects the body's chemistry and metabolism using PET scanning and other imaging technologies.

Animal models: Scientists hope to learn more about the symptoms and progression of the disease by breeding laboratory animals, such as mice, and attempting to duplicate the clinical features of HD.

Genetic studies: Scientists are continuing to study inheritance patterns in families, including genetic studies of onset age, inheritance patterns and markers found within families. These studies may shed additional light on how HD is passed from generation to generation.

Clinical trials of drugs: Drug testing includes classes of drugs that control symptoms, slow the rate of progression of HD or correct or replace other metabolic defects contributing to the development and progression of HD. The latest and most promising strategy is to use a therapeutic that reduces levels of the mutant form of Huntingtin in the brain.

Clinical trial shows Huntington's drug could slow disease progression

Source: http://www.genome.gov/10001215

Chronic Wasting Disease

Chronic wasting disease (CWD) is a contagious prion disease that affects multiple species of deer, elk, moose, and reindeer. Signs of illness from CWD may include weight loss, stumbling, excessive salivation, and other neurologic abnormalities. The rising number of cases and locations globally increases the potential threat to wildlife and humans.

Currently, CWD has been identified in the United States, Canada, Norway, and South Korea. According to the Montana Fish, Wildlife & Parks’ 2017 and 2020 Chronic Wasting Disease Surveillance and Monitoring Report, in 2017 Montana found 11 positive CWD cases, and only 3 years later in 2020 there were 271.

The risk to humans is unclear at this time with conflicting results from scientific investigations (1–3). It is imperative to better evaluate the risk of transmission to humans and contain the spread of CWD in cervids. Unknown future ecological impacts, the possibility of iatrogenic spread in humans though surgical instruments, and risk to domestic livestock(4) are just a few among the long list of potential threats.  CWD is a fatal disease for which there is no effective vaccine or treatment, and decontamination of the environment is exceedingly difficult (5,6). 

1.         Wang Z, Qin K, Camacho MV, et al. Generation of human chronic wasting disease in transgenic mice. Acta Neuropathol Commun. 2021;9(1):158. doi:10.1186/s40478-021-01262-y

2.         Race B, Williams K, Chesebro B. Transmission studies of chronic wasting disease to transgenic mice overexpressing human prion protein using the RT-QuIC assay. Vet Res. 2019;50(1):6. doi:10.1186/s13567-019-0626-2

3.         Race B, Williams K, Orrú CD, Hughson AG, Lubke L, Chesebro B. Lack of Transmission of Chronic Wasting Disease to Cynomolgus Macaques. Pfeiffer JK, ed. J Virol. 2018;92(14). doi:10.1128/JVI.00550-18

4.         Madsen-Bouterse SA, Schneider DA, Zhuang D, et al. Primary transmission of chronic wasting disease versus scrapie prions from small ruminants to transgenic mice expressing ovine or cervid prion protein. J Gen Virol. 2016;97(9):2451-2460. doi:10.1099/jgv.0.000539

5.         Pritzkow S, Morales R, Moda F, et al. Grass Plants Bind, Retain, Uptake, and Transport Infectious Prions. Cell Rep. 2015;11(8):1168-1175. doi:10.1016/j.celrep.2015.04.036

6.         Nichols TA, Fischer JW, Spraker TR, Kong Q, VerCauteren KC. CWD prions remain infectious after passage through the digestive system of coyotes ( Canis latrans ). Prion. 2015;9(5):367-375. doi:10.1080/19336896.2015.1086061