Dystonia as a presenting feature of the 3243 mitochondrial DNA mutation

A variety of neurologic phenotypes have been described in patients with mit ochondrial disorders. We report a 32-year-old man in whom dystonia was the salient and presenting feature of a mitochondrial DNA mutation. He presente d at age 23 with writer's cramp and progressed over 5 years to exhibit dyst onia in facial muscles and lower limbs. He also has exercise intolerance, m ild, bilateral ptosis, proximal muscle weakness, and sensorineural hearing loss. Molecular genetic analysis of blood, urine, and muscle biopsy demonst rated the presence of a heteroplasmic point mutation at nucleotide position 3243. The 3243 mtDNA mutation has pleomorphic manifestations, and dystonia should be added to the list of associated clinical features.