Reduced expression of TMEM106B mRNA in Alzheimer’s disease brains. TMEM106B and progranulin (PGRN) mRNA expression levels were studied by quantitative reverse transcriptase-polymerase chain reaction (qPCR) in human brain tissues derived from a reference of the human frontal cortex (REF), four non-neurological control cases (NC), six amyotrophic lateral sclerosis (ALS) cases, four Parkinson’s disease (PD) cases, and seven Alzheimer’s disease (AD) cases. The expression levels were standardized against those of G3PDH. (a) TMEM106B mRNA expression. (b) PGRN mRNA expression. (c) Difference in TMEM106B levels between AD and non-AD cases. *P = 0.0035 by Student’s t test. (d) Difference in PGRN levels between AD and non-AD cases. **P = 0.0027 by Student’s t test. (e) Pearson’s correlation between TMEM106B and PGRN mRNA levels. Pearson’s correlation coefficient indicates −0.555 (P = 0.0090).