ABSTRACT: Abstract: Objective: Adenomyosis is a clinical disorder defined by the presence of endometrial glands and stroma within the myometrium, the pathogenesis of which is poorly understood. We postulate that dysregulation of genes and pathways in eutopic endometrium may predispose to ectopic implantation. No study, to our knowledge, has examined the global transcriptome of isolated eutopic endometrium from women with clinically significant adenomyosis. Design: Laboratory-based study with full IRB approval and consents. Material and Methods: Endometrial sampling was performed on hysterectomy specimens (proliferative phase) from symptomatic women with pathologically-confirmed diffuse adenomyosis (n=3). Controls (n=5) were normo-ovulatory subjects without adenomyosis. All subjects were free from leiomyoma, endometriosis, and hormonal exposures. Isolated purified total RNA was subjected to microarray analysis using the Gene 1.0 ST Affymetrix platform. Data were analyzed with GeneSpring and Ingenuity Pathway analysis. Validation of several genes was undertaken by QRT-PCR. Results: Comparison of transcriptomes of proliferative endometrium from women with and without adenomyosis revealed 140 up-regulated and 884 down-regulated genes in samples from women with adenomyosis compared to controls. Highly differentially expressed genes include those involved in regulation of apoptopsis, steroid hormone responsiveness, and proteins involved in extracellular matrix remodeling, as well as microRNAs of unknown significance. Affected canonical pathways included eukaryotic initiation factor 2 signaling, oxidative phosphorylation, mitochondrial dysfunction, estrogen receptor signaling, and mTOR signaling. Conclusions: The eutopic endometrium in patients with adenomyosis has fundamental abnormalities that may predispose to invasion and survival beyond the myometrial interface. Key Words: adenomyosis, endometrium, microarray, microRNA, endometriosis, apoptosis, signaling. Abstract: Objective: Adenomyosis is a clinical disorder defined by the presence of endometrial glands and stroma within the myometrium, the pathogenesis of which is poorly understood. We postulate that dysregulation of genes and pathways in eutopic endometrium may predispose to ectopic implantation. No study, to our knowledge, has examined the global transcriptome of isolated eutopic endometrium from women with clinically significant adenomyosis. Design: Laboratory-based study with full IRB approval and consents. Material and Methods: Endometrial sampling was performed on hysterectomy specimens (proliferative phase) from symptomatic women with pathologically-confirmed diffuse adenomyosis (n=3). Controls (n=5) were normo-ovulatory subjects without adenomyosis. All subjects were free from leiomyoma, endometriosis, and hormonal exposures. Isolated purified total RNA was subjected to microarray analysis using the Gene 1.0 ST Affymetrix platform. Data were analyzed with GeneSpring and Ingenuity Pathway analysis. Validation of several genes was undertaken by QRT-PCR. Results: Comparison of transcriptomes of proliferative endometrium from women with and without adenomyosis revealed 140 up-regulated and 884 down-regulated genes in samples from women with adenomyosis compared to controls. Highly differentially expressed genes include those involved in regulation of apoptopsis, steroid hormone responsiveness, and proteins involved in extracellular matrix remodeling, as well as microRNAs of unknown significance. Affected canonical pathways included eukaryotic initiation factor 2 signaling, oxidative phosphorylation, mitochondrial dysfunction, estrogen receptor signaling, and mTOR signaling. Conclusions: The eutopic endometrium in patients with adenomyosis has fundamental abnormalities that may predispose to invasion and survival beyond the myometrial interface. Key Words: adenomyosis, endometrium, microarray, microRNA, endometriosis, apoptosis, signaling.