cDNA microarray and bioinformatic analysis for the identification of key genes in Alzheimer's disease.

In this study, gene expression profiles in peripheral blood monocytes from patients with Alzheimer's disease (AD) or mild cognitive impairment (MCI) were compared with those of healthy individuals to identify key differentially expressed genes (DEGs), in an effort to broaden our understanding of the pathogenesis of these diseases and identify potential therapeutic targets. The microarray data set GSE18309 was downloaded from Gene Expression Omnibus, including 3 AD, 3 MCI and 3 normal control (NC) samples. Raw data were processed and differential analysis was performed using the R multtest package. Two groups of comparisons (AD vs. NC and MCI vs. NC) were conducted and two groups of DEGs were acquired. The common DEGs were selected, for which functional enrichment analysis, as well as pathway enrichment analysis were performed to determine their roles in the development of the diseases in question. A total of 405 DEGs were identified in the AD vs. NC samples and 395 in the MCI vs. NC samples. A total of 60 common DEGs were obtained. Functional enrichment analysis revealed that the most common functions of the DEGs identified were response to nutrients, muscle contraction and cellular homeostasis. As shown by pathway enrichment analysis, the most common pathway associated with the DEGs identifed was the neuroactive ligand-receptor interaction pathway. A range of DEGs was identified in the present study, which may help to disclose the molecular mechanisms responsible for AD and may thus provide potential novel therapeutic strategies for Ad.