Defects of GnRH neuron activity or migration are thought to be the primary cellular cause of congenital disorders known as Kallmann Syndrome and Central Hypogonadotropic Hypogonadism, characterized by delayed sexual maturation and hypofertility (Cariboni and Maggi, 2006; Boehm et al., 2015). The gene discussed is GNRH1; the disease is Kallmann syndrome.