A loss-of-function mutation of GNAS1 results in follicle-stimulating hormone (FSH) resistance (among other symptoms) when the gene is MI but not when it is PI. FSH resistance results in reduced ovarian follicle stock and premature ovarian failure. Thus a loss-of-function mutation of GNAS1 results in premature ovarian failure when MI but not when PI. Greater expression of GNAS1 contributes to greater fertility thus acting as a fertility enhancer. Here, GNAS is linked to primary ovarian failure.