Objective: The etiology of PCOS is mostly unknown. Existing data support both genetic and environmental factors in its pathogenesis. Design: Prospective case - control study. Setting: University Hospital. Patients: 25 patients undergoing IVF-ICSI treatment. Intervention: Genome-wide oligonucleotide microarray technology was used to study differential gene-expression patterns of cultured human cumulus cells from IVF patients divided into 4 groups according to disease state (PCOS vs. Control) and BMI (Obese vs. Lean). Results: Two differential PCOS gene expression profiles were established: Lean-Type was formed by comparing PCOS lean (PL) vs. non-PCOS lean (NL) individuals; Obese-Type was formed by comparing PCOS obese (PO) vs. non-PCOS (NO) obese patients. Conclusions: Different molecular pathways are associated with PCOS in Lean and Obese individuals, as demonstrated by gene expression profiling of cumulus cells. Our findings provide insights into the molecular pathogenesis of PCOS.We used microarrays to study the gene expression of human cultured cumulus cells. We compared the genes expression of lean PCOS, Obese PCOS, lean controls and obese controls. Different molecular pathways are associated with PCOS in Lean and Obese patients.Keywords: disease state analysis

Cumulus cells obtained from woman undergoing IVF/ICSI. Following oocyte retrieval, cumulus cells were stripped from the oocyte, in preparation for the ICSI process, with a micropipette. After 48h in culture the cumulus cells were collected for RNA extraction and hybridization on Affymetrix microarrays. We compered the expression profile of 4 groups - lean PCOS, obese PCOS, lean controls and obese controls.