COMT and deafness: Du and co-workers documented several severe malformations in a COMT missense murine model, including abnormal auditory startle response, impaired movement behavior, and loss of inner and outer hair cells with degeneration of cochlear neurons and vestibular defects, collectively causing deafness and degeneration of the vestibular sensory/balancing system in mice by 8 weeks of age (Menendez et al., 2017).