Mohr–Tranebjærg syndrome (MTS) is a rare X-linked recessive syndrome also known as deafness–dystonia syndrome and caused by mutation in the TIMM8A gene. It is characterized by clinical manifestations commencing with early childhood onset hearing loss, followed by adolescent onset progressive dystonia or ataxia, visual impairment from early adulthood onwards and dementia from the 4th decade onwards. The severity of the symptoms may vary, but they progress usually to severe deafness and dystonia and sometimes are accompanied by cortical deterioration of vision and mental deterioration. Signs and Symptoms
Mohr-Tranebjærg is characterized by a variety of symptoms affecting hearing loss. In the span of a subject with Mohr-Tranebjærg, by the age of early childhood, around 18 months, the development of quickly progressive prelingual or postlingual sensorineural hearing loss. The presence of auditory symptoms is characterized by preserved oto-acoustic emissions, abnormal auditory brain stem response, poor speech, and worsening in auditory symptoms even with auditory devices. Also, neuropsychological manifestations, possibly consisting of personality changes, paranoia, and mild intellectual deficit could emerge. During adolescence, there is a possibility that a slowly progressive movement disorder, similar to gegenhalten, dystonia, or ataxia could develop. Patients with Mohr-Tranebjærg experience reduced visual acuity, photophobia, acquired color vision defect and central scotomas developing at around 20 years of age, and leading to more severe blindness by age 30 or 40.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.
Because of the statistical probabilities that each sex inherits the syndrome, males are affected by Mohr-Tranebjærg more frequently than females are. Females who carry one copy of the TIMM8A gene (described in Genetics) are usually unaffected, however, may develop mild hearing loss and dystonia. Prognosis
Prognosis is poor. The combination of deafness and blindness severely affects communication, while the ongoing movement disorder results in an increasingly unstable gait. Life expectancy is highly variable and can range from death in the teenage years (after a rapidly progressive dystonia) to those that live into their 60s. History
This condition was first described in 1960. Epidemiology
Mohr-Tranebjᴂrg syndrome (MTS) prevalence is unknown. More than 90 cases (in 37 families) are known, but not all cases have been reported in the literature. See also
Mitochondrial disorders
TIMM13 and TIMM8A

References
External links

GeneReviews/NCBI/NIH/UW entry on Deafness–Dystonia–Optic Neuronopathy Syndrome
MTS — a page at NIH website