Mutations in SEMA3A and SEMA3E (Hanchate et al., 2012; Young et al., 2012; Känsäkoski et al., 2014; Cariboni et al., 2015) have been found in patients with Kallmann syndrome (KS), which is due to a defect in the migration of GnRH neurons during development and share some phenotypic features with CHARGE syndrome (Dodé and Hardelin, 2009) (see also section “GnRH Neurons”). The gene discussed is SEMA3A; the disease is CHARGE syndrome.