Genes drive the biological functions that characterize and distinguish tissue types. The levels and timing of gene expression govern cellular development, differentiation, function and physiology. In an effort to better understand the etiology of endometriosis, a disease affecting 10% of all women of child bearing age, we are studying the genes expressed in unaffected and endometriosis-affected women. Normal endometrium consists of proliferative, secretory and glandular epithelia, and stromal and vascular elements. The epithelial cells synchronously proliferate, then differentiate and disintegrate at 28 day intervals. Proliferation is the dominant activity during days 4-13 of the menstrual cycle. During the proliferative phase the endometrium thickens and is characterized by mitoses within the glandular epithelium and pseudostratification of nuclei. After ovulation occurs the secretory phase begins (days 14-28) characterized first by basal vacuolation and secretion in glandular epithelium and later stromal edema and predecidual reaction. Until recently it has not been possible to simultaneously and quantitatively measure the expression levels of the thousands of human genes that characterize endometrial tissue and that distinguish normally functioning tissue from disease affected tissue. Using GeneChip(R) probe array (chip) technology we are able to simultaneously measure the relative concentrations of thousands of mRNAs in a single experiment. In Phase 1 using chips containing probes for approximately 7200 human genes we will: 1) Identify genes expressed in normal endometrium during the proliferative phase of the human menstrual cycle. 2) Identify stage I-IV endometriosis associated gene expression differences in proliferative endometrium. 3) Identify expression differences associated with endometriosis stage II, III, and IV proliferative endometrium, peritoneal lesions and ovarian endometriomas using matched samples. Only recently, with the development of the oligonucleotide array technology for gene expression monitoring, has a project of this scope become feasible
