Leveraging a testing method called a real-time quaking induced conversion assay, originally used to detect mad cow disease, Iowa State University researchers have created a simple skin test that can accurately provide early identification of Parkinson’s disease (PD). No assays have been developed to date for identifying PD. Instead, the disease is diagnosed via clinical symptoms of patients and neurological testing, with a definitive diagnosis only possible via autopsy.
The research, published in the scientific journal Movement Disorders, demonstrates how the real-time quaking conversion assay can detect clumping of the protein alpha-synuclein in skin samples to help diagnose Parkinson’s disease (PD). The study’s authors say that using the assay can lead to earlier detection of PD and, since it can identify patients with early onset of the disease, aid better recruitment for clinical trials.
“Since there’s no easy and reliable test available for the early diagnosis of Parkinson’s disease at present, we think there will be a lot interest in the potential use of skin samples for diagnosis,” said Anumantha Kanthasamy, Distinguished Professor of Biomedical Sciences at Iowa State and lead author of the study.
Kanthasamy’s lab has spent several years optimizing the assay for detecting misfolded proteins in similar human and animal disorders. Parkinson’s disease arises from misfolded alpha-synuclein proteins that accumulate in the brain leading to neuronal damage. Co-investigators in the research Charles Adler, M.D., professor of neurology at Mayo Clinic Arizona, and Thomas Beach, MD, head of the Civin Laboratory at Banner Sun Health Research Institute, have previously led research at the Arizona Study of Aging and Neurodegenerative Disorders (AZSAND)/Brain and Body Donation Program that has found these misfolded alpha-synuclein proteins also collect in other body tissues as well, including the skin.
“The clinical diagnostic accuracy for early-stage PD has been quite poor, only around 50-70%. And since clinical trials really need to be done at an early stage to avoid further brain damage, they have been critically hampered because they have been including large percentages of people who may not actually have the disease,” said Beach. “Improving clinical diagnostic accuracy is, in my view, the very first thing we need to do in order to find new useful treatments for PD.”
The researchers conducted a blinded study of 50 skin samples provided by AZSAND. Half of the skin samples came from patients with Parkinson’s disease and half came from people without neurologic disease. Using the protein assay correctly diagnosed 24/25 Parkinson’s disease patients and only 1/25 controls had the protein clumping. Adler noted that “these results indicate tremendously high sensitivity and specificity which is critical for a diagnostic test.”