CHD7 and Hearing impairment: Indeed, chemical mutagenesis has successfully produced a number of mouse mutants with mutations in the gene for chromodomain helicase DNA-binding protein-7 (Chd7, MGI: 2444748) [16], which now serve as mouse models for CHARGE syndrome (OMIM #214800; CHD7, OMIM *608892), a form of syndromic hearing impairment [17].