The Search for the Causes of Common Hyperandrogenism, 1965 to circa 2015

Abstract From 1965-2015, immense strides were made into understanding the mechanisms underlying the common androgen excess disorders, premature adrenarche and polycystic ovary syndrome (PCOS). The author reviews the critical discoveries of this era from his perspective investigating these disorders, commencing with his early discoveries of the unique pattern of plasma androgens in premature adrenarche and the elevation of an index of the plasma free testosterone concentration in most hirsute women. The molecular genetic basis, though not the developmental biologic basis, for adrenarche is now known and 11-oxytestosterones shown to be major bioactive adrenal androgens. The evolution of the lines of research into the pathogenesis of PCOS is historically traced: research milestones are cited in the areas of neuroendocrinology; insulin resistance, hyperinsulinism, type 2 diabetes mellitus; folliculogenesis; androgen secretion; obesity; phenotyping, prenatal androgenization, epigenetics, and complex genetics. Large scale genome-wide association studies led to the 2014 discovery of an unsuspected steroidogenic regulator DENND1A (differentially expressed in normal and neoplastic development). The splice variant DENND1A.V2 is constitutively overexpressed in PCOS theca cells in long-term culture and accounts for their PCOS-like phenotype. The genetics are complex, however: DENND1A intronic variant copy number is related to phenotype severity, and recent data indicates that rare variants in a DENND1A regulatory network and other genes are related to PCOS. Obesity exacerbates PCOS manifestations via insulin resistance and pro-inflammatory cytokine excess; excess adipose tissue also forms testosterone. Polycystic ovaries in one-quarter of apparently normal women lie on the PCOS functional spectrum. Much remains to be learned.