Observations of people with single-gene causes of IR, or reversible severe IR due to INSR-blocking autoantibodies, establish that primary IR is sufficient to induce changes indistinguishable from PCOS, as long as secretion of gonadotrophin hormones from the pituitary gland is intact (Huang-Doran et al., 2021). Here, INSR is linked to polycystic ovary syndrome.