Cyc1 is commonly used as a RT-qPCR reference gene in the central nervous system and was among the most stably expressed genes during the study of several neurodegenerative diseases (Alzheimer’s disease, Parkinson’s disease, multiple system atrophy, and progressive supranuclear palsy) in human prefrontal cortex and cerebellum tissue samples [41]. Here, CYC1 is linked to Parkinson disease.