CHD7 and CHARGE syndrome: Previous studies on the pathogenic role of CHD7 RSVs mainly focused on CHARGE syndrome, In 2008, Kim et al. (2008) first showed that Chd7 mRNA expressed in the CHH/KS-relevant organs of rats (including migratory and post-migratory GnRH neuron, olfactory bulb, pituitary, and hypothalamus), and the pathogenic variants can exist in both nCHH and KS without CHARGE-related phenotype.