Prion diseases are rare conditions similar to those caused by viruses that are caused by misfolded proteins known as prions. The most well-known of these is the neuro-degenerative Creutzfeldt-Jakob disease, which is commonly known for the way it appears in cows as Mad Cow disease. But according to a recent study, multiple system atrophy (MSA), another neurological disorder, can also be classified as a prion disease. The findings, published in the Proceedings of the National Academy of Sciences, suggest there are unseen ways in which MSA can be transmitted, and may even lead to possible treatment options.

First identified in 1960, MSA is an extremely rare condition that impairs the body’s involuntary functions. Its symptoms are similar to those that characterize Parkinson’s disease, including slowed movement and trouble with balance. These symptoms eventually lead to the patient’s death. While the cause of MSA was never fully understood, Kurt Giles, senior author of the recent study, said his team has now “conclusively shown that a new type of prion causes MSA.”

The findings mark the first time in 50 years that a human disease has been found to be caused by a new prion. For the study, the team exposed human MSA tissue to mice, which then went on to experience neurodegeneration. Exposure to brain tissue from these mice could then cause the disease to spread to other mice. The team observed that the culprit was a misfolded version of a protein called alpha-synuclein, which not only allowed the disease to spread from human tissue to mouse, but also to human cell cultures.

Prion diseases are a group of conditions that affect the nervous system in humans and animals. The most common symptoms of prion diseases in humans are impaired brain function and difficulty coordinating movements. These symptoms usually worsen over time and inevitably lead to the patient’s death.

"You can't kill a protein," Giles said in a statement. "And it can stick tightly to stainless steel, even when the surgical instrument is cleaned." Due to this unforeseen danger, Giles suggests more emphasis should be put on cleaning surgical equipment. "People are living longer and likely getting more brain surgeries. There could be undiagnosed neurodegenerative diseases that, if they're caused by prions, mean infection could be a real worry."

Other researchers are less convinced that the study suggests people are at an increased risk of human-to-human transmission. According to Dr. Valerie Sim, a prion expert at the University of Alberta in Canada, the research “suggests MSA does not transmit easily,” NBC reported.

Identifying MSA as a prion disease is a major step forward for the medical community. There is currently no cure for MSA, a disease that affects 15,000 to 50,000 Americans. However, now that scientists know exactly what causes the condition, they will more prepared to tackle it.

Source: Giles K, Prusiner SB, Woerman AL, et al. Evidence for α-synuclein prions causing multiple system atrophy in humans with parkinsonism. PNAS. 2015.