A simple skin biopsy test is able to detect an abnormal form of alpha-synuclein with high accuracy in individuals with neurodegenerative disorders such as Parkinson’s disease (PD).
Synucleinopathies include PD, dementia with Lewy bodies (DLB), multiple system atrophy (MSA), and pure autonomic failure (PAF).
“Each year, there are nearly 200,000 people in the U.S. who face a diagnosis of Parkinson’s disease, dementia with Lewy bodies, and related disorders,” study investigator Christopher H. Gibbons, MD, professor of neurology at Harvard Medical School in Boston, said in a press release.
He explained that patients often experience delays in diagnosis or are misdiagnosed due to the complexity of synucleinopathies.
“With a simple, minimally invasive skin biopsy test, this blinded, multicenter study demonstrated how we can more objectively identify the underlying pathology of synucleinopathies and offer better diagnostic answers and care for patients.”
The findings were published online on March 20 in JAMA.
An Urgent Priority
Affecting an estimated 2.5 million people in the United States, synucleinopathies are progressive neurodegenerative diseases with varying prognoses, so identifying a reliable diagnostic biomarker is an “urgent unmet priority,” the researchers noted.
The disorders share some symptoms such as tremors and cognitive changes, and all are characterized by P-SYN, an abnormal protein found in the cutaneous nerve fibers.
The study included 428 adults aged 40-99 years (mean age, 70 years) recruited from 30 academic and community-based neurology practices across the United States, with 277 diagnosed with PD, DLB, MSA, or PAF. It also included a control group of 120 participants with no symptoms suggestive of synucleinopathy.
Investigators used the commercially available Syn-One Test, developed in 2019 by CND Life Sciences, to analyze levels of P-SYN via 3-mm punch skin biopsies from each participant.
The test detected P-SYN in 95.5% of study participants overall, including 89 of 96 (92.7%) with PD, 54 of 55 (98.2%) with MSA, 48 of 50 (96%) with DLB, 22 of 22 (100%) with PAF, and 4 of 120 (3.3%) of the controls with no synucleinopathy.
The investigators said it is possible that some of the controls who tested positive had a subclinical form of synucleinopathy, which would explain the false positives.
Study limitations include clinical consensus diagnostic criteria without video or autopsy confirmation, a lack of genetic testing on participants (some genetic forms of PD do not have alpha-synuclein deposition), and the fact that controls were younger than those in disease groups.
“Further research is needed in unselected clinical populations to externally validate the findings and fully characterize the potential role of skin biopsy detection of P-SYN in clinical care,” the authors wrote.
Syn-One is not approved by the US Food and Drug Administration as a diagnostic test for PD but is available as a pathologic assay that determines whether a tissue sample contains phosphorylated alpha-synuclein and can be billed through Medicare.
The study was funded by the National Institutes of Health. Dr. Gibbons reported having stock options in CND Life Sciences outside the submitted work. Other disclosures are noted in the original article.
A version of this article appeared on Medscape.com.