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General introduction171 integrated with input from other sensory systems to guide behavior and movement.50 Sensory systems play an important role in communication, building and maintaining social interactions, and signaling of danger. Deficits may result in accidents, including falling, and may cause or aggravate symptoms of anxiety and depression.51, 52Individuals with an intellectual disability, as a group, were reported to have an increased risk of hearing and/or vision loss at an earlier age compared to individuals from the general population.53 Knowledge of sensory (dys)function in GNDs, except for Down syndrome,11, 54-56 is however limited. The following paragraphs give a general introduction to the auditory and ophthalmic system and to what is known so far in individuals with 22q11.2DS.Hearing and otologic findingsHearing can be tested with audiometry, which makes it possible to differentiate between types of hearing loss and to describe the configuration of hearing thresholds in terms of severity and frequencies (tones) that are affected.57 Hearing loss can be conductive, resulting from problems in the middle and/or external ear, sensorineural, resulting from cochlear damage, or mixed.58 Conductive hearing loss may be caused by, for example, ear wax or fluid in the middle ear, and sensorineural hearing loss may be caused by noise damage, medication or aging.58 Depending on the severity and type of hearing loss, hearing aids can be prescribed.58In a large sample of adults with an intellectual disability hearing loss was found in about 35%, which is higher compared to the general population.59The global estimate of hearing loss is 20% in the general population and increases with age, most notably after the age of 50 years.60 Age-related hearing loss in the general population affects 40% of individuals aged 65 years and older.61 It starts with a high-tone loss, which has an adverse effect on hearing sensitivity and speech understanding with background noise, and in a more advanced state, on localization of sounds.61, 62In 22q11.2DS, there have been several studies examining hearing and otologic problems in children, with only a few that included adults.35, 63-66