The protein that recognizes and binds to the specific epigenetic modification is called “reader”. For example, acetylated lysine can be selectively recognized by a reader protein motif called bromodomain. At least 43 bromodomain-containing proteins have been identified in the human genome, most of which are important transcriptional regulators. Certain human diseases have been found to be associated with mutations in the bromodomain. Although the bromodomain has received significant attention in biomedical research, abnormalities in other reader protein domains also have significant physiological effects.