Deafness-dystonia-optic neuronopathy syndrome

Deafness-dystonia-optic neuronopathy (DDON) syndrome, also known as Mohr-Tranebjærg syndrome, is characterized by hearing loss that begins early in life, problems with movement, impaired vision, and behavior problems. This condition occurs almost exclusively in males.

The first symptom of DDON syndrome is hearing loss caused by nerve damage in the inner ear (sensorineural hearing loss), which begins in early childhood. The hearing impairment worsens over time, and most affected individuals have profound hearing loss by age 10.

People with DDON syndrome typically begin to develop problems with movement during their teens, although the onset of these symptoms varies among affected individuals. Some people experience involuntary tensing of the muscles (dystonia), while others have difficulty coordinating movements (ataxia). The problems with movement usually worsen over time.

Individuals with DDON syndrome have normal vision during childhood, but they may develop vision problems due to breakdown of the nerves that carry information from the eyes to the brain (optic atrophy). Affected individuals can develop an increased sensitivity to light (photophobia) or other vision problems beginning in adolescence. Their sharpness of vision (visual acuity) slowly worsens, often leading to legal blindness in mid-adulthood.

People with this condition may also have behavior problems, including changes in personality and aggressive or paranoid behaviors. They also usually develop a gradual decline in thinking and reasoning abilities (dementia) in their forties. The lifespan of individuals with DDON syndrome depends on the severity of the disorder. People with severe cases have survived into their teenage years, while those with milder cases have lived into their sixties.