Auditory neuropathy spectrum disorder (ANSD) is a rare condition that can affect a person's ability to hear. Although sounds enter the inner ear normally, signals from the inner ear to the brain are not transmitted properly. As a result, the condition may be associated with mild to severe hearing loss and poor speech-perception abilities (difficulty understanding speech clearly). ANSD can be associated with other neurological disorders such as Friedrich ataxia, Stevens-Johnson syndrome, Ehlers-Danlos syndrome, and Charcot-Marie-Tooth syndrome. The exact underlying cause of ANSD is not completely understood; however, researchers have proposed many possible explanations including damage to the hair cells of the inner ears, faulty connections between the hair cells and the auditory nerve (the nerve connecting the inner ear to the brain), damage to the auditory nerve, and/or a combination of these abnormalities. In many cases, ANSD occurs sporadically in people with no family history of the condition; however, the condition does run in some families suggesting that genetic factors may play a role in some cases. Treatment varies based on the severity of the condition but aims to improve hearing (i.e. hearing aids and cochlear implants) and communication skills.