The disclosure is directed in non-limiting embodiments to compounds, compositions, and methods of treating conditions and diseases associated with activation of the gonadotropin GnRH receptor (GnRHR), particularly those involving GnRHR activating autoantibodies (GnRHR AAbs). In one non-limiting embodiment, the disease is Polycystic Ovary Syndrome (PCOS). The therapeutic compounds in at least certain embodiments include peptides which at least partially comprise D-amino acids, such as retro-inverso D-amino acid (RID) peptides, which are able to bind with high affinity to GnRHR AAbs.