Gene mutations contributing to the disruption of pituitary development can themselves be classified: mutations affecting transcriptional determinants of pituitary development, mutations causal to gonadotropin deficiency, mutations affecting the beta subunit of FSH and LH, and mutations in the DAX-1 gene as a cause of adrenal hypoplasia and of disturbed responsiveness of the pituitary to GnRH (Table 1). This evidence concerns the gene PLOD1 and chronic primary adrenal insufficiency.