posted on 2021-02-12, 16:45authored byEleanor Sinclair, Caitlin Walton-Doyle, Depanjan Sarkar, Katherine A. Hollywood, Joy Milne, Sze Hway Lim, Tilo Kunath, Anouk M. Rijs, Rob M. A. de Bie, Monty Silverdale, Drupad K. Trivedi, Perdita Barran
Parkinson’s
disease (PD) is a progressive neurodegenerative
disorder that does not currently have a robust clinical diagnostic
test. Nonmotor symptoms such as skin disorders have long since been
associated with the disease, and more recently a characteristic odor
emanating from the skin of people with Parkinson’s has been
identified. Here, dynamic head space (DHS) thermal desorption (TD)
gas chromatography–mass spectrometry (GC-MS) is implemented
to directly measure the volatile components of sebum on swabs sampled
from people with Parkinson’sboth drug naïve
and those on PD medications (n = 100) and control
subjects (n = 29). Supervised multivariate analyses
of data showed 84.4% correct classification of PD cases using all
detected volatile compounds. Variable importance in projection (VIP)
scores were generated from these data, which revealed eight features
with VIP > 1 and p < 0.05 which all presented
a downregulation within the control cohorts. Purified standards based
on previously annotated analytes of interest eicosane and octadecanal
did not match to patient sample data, although multiple metabolite
features are annotated with these compounds all with high spectral
matches indicating the presence of a series of similar structured
species. DHS-TD-GC-MS analysis of a range of lipid standards has revealed
the presence of common hydrocarbon species rather than differentiated
intact compounds which are hypothesized to be breakdown products of
lipids. This replication study validates that a differential volatile
profile between control and PD cohorts can be measured using an analytical
method that measures volatile compounds directly from skin swabs.