Previously, the occurrence a pre-ovulatory progesterone rise has been reported by Hoff et al.23 The role of this pre-ovulatory progesterone has been proposed to be triggering the LH surge and a premature rise in this has been indicated in the pathology of poly-cystic ovarian syndrome (PCOS)24,25. Here, PLOD1 is linked to polycystic ovary syndrome.