Neither patient had clinical features of Waardenburg syndrome type 4 associated with constitutional defects in the SOX10 gene (Online Mendelian Inheritance in Man # 613266), including sensorineural hearing loss, abnormal pigmentation of the hair and skin, aganglionic megacolon (Hirschsprung disease), peripheral demyelinating neuropathy, central dysmyelinating leukodystrophy, and seizures/tremors. The gene discussed is SOX10; the disease is Hirschsprung disease.