The qPCR analysis of 46 individuals with RBD (mean age 65 years, range 34-83 years, with 36 males; since sampling, five individuals have converted to PD and one to Lewy body dementia, without DATscan confirmation) versus 19 matched controls (mean age 61 years, range 30-74 years, with 12 males) failed to detect a significant increase in GZMH (P=0.29), SPP1 (P=0.35; but upon exclusion of one exceptionally high value among controls, an upregulation to 174% with P=0.04 was observed) and PLTP (P=0.66). Here, PLTP is linked to Parkinson disease.