Hypermanganesemia with dystonia-2 (HMNDYT2) is an autosomal recessive neurodegenerative disorder characterized predominantly by loss of motor milestones in the first years of life. Affected individuals then develop rapidly progressive abnormal movements, including dystonia, spasticity, bulbar dysfunction, and variable features of parkinsonism, causing loss of ambulation. Cognition may be impaired, but is better preserved than motor function. The disorder results from abnormal accumulation of manganese (Mn), which is toxic to neurons. Chelation therapy, if started early, may provide clinical benefit. [From OMIM]