The authors in [17] demonstrated that TUBB2A in reduced expression reasonably predicted PD as a blood biomarker via a meta-analysis of 11 datasets from GEO (8 from substantia nigra and 3 from blood samples) with further validation analyzing mRNA expression levels in the blood of 50 sporadic PD patients and 50 control subjects. The gene discussed is TUBB2A; the disease is Parkinson disease.