GNRH1 and central precocious puberty: Central precocious puberty (CPP) is defined as a premature activation of the hypothalamic-pituitary-gonadal (HPG) axis causing pulsatile hypothalamic secretion of gonadotropin-releasing hormone (GnRH) that consequently increases concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).