Ubiquitin levels were significantly high (36.8 ± 4.34 ng/mL) in AD patients compared to those in non-AD (23.6 ± 2.32 ng/mL), neurological controls (19.8 ± 3.64 ng/mL), and healthy controls (13.2 ± 4.56 ng/mL). The gene discussed is RPS27A; the disease is Alzheimer disease.