Incomplete penetrance in Chd7+/Whi mutants has been well documented for other phenotypes (eye defects, genital anomalies, cardiovascular defects, cleft palate and choanal atresia), although it is noteworthy that not all phenotypes have the same degree of incomplete penetrance, which makes the Chd7+/Whi mutant a very interesting CHARGE syndrome model since individuals with CHARGE syndrome share the same principle of phenotypic variability. This evidence concerns the gene CHD7 and choanal atresia.