FGFR1 and hypogonadotropic hypogonadism: Rare naturally occurring FGFR1 mutations contribute to approximately 12% of the genetic etiology of isolated hypogonadotropic hypogonadism (IHH) with or without anosmia, a rare inherited disorder of infertility that is caused by deficiency in the hypothalamic secretion of the gonadotropin-releasing hormone (GnRH) [11].