PAX3 and Hydrocephalus: While other Waardenburg patients with hydrocephalus can carry chromosomal inversions and insertions that do not affect the coding sequence of the PAX3 gene, those with mutations in the regulatory gene(s) for PAX3 [38], the PAX3 promoter, or the 5′ untranslated region of PAX3 [39] are more likely to exhibit phenotypes.