MERRF Syndrome

**Definition:** A mitochondrial encephalomyopathy characterized clinically by a mixed seizure disorder, myoclonus, progressive ataxia, spasticity, and a mild myopathy. Dysarthria, optic atrophy, growth retardation, deafness, and dementia may also occur. This condition tends to present in childhood and to be transmitted via maternal lineage. Muscle biopsies reveal ragged-red fibers and respiratory chain enzymatic defects. (From Adams et al., Principles of Neurology, 6th ed, p986)

**Tree numbers:** - C05.651.460.620.530 - C10.228.140.163.100.545 - C10.228.140.490.375.130.650.700 - C10.228.140.490.493.063.650.700 - C10.668.491.500.500.550 - C16.320.565.189.545 - C18.452.132.100.545 - C18.452.648.189.545 - C18.452.660.560.620.530

**Synonyms:** - Myoclonic Epilepsy with Ragged Red Fibers - Fukuhara Syndrome - Myoclonic Epilepsy and Ragged Red Fibers - Myoclonus with Epilepsy with Ragged Red Fibers - Myoencephalopathy Ragged-Red Fiber Disease - Myoclonic Epilepsy Associated with Ragged-Red Fibers - Myoclonic Epilepsy with Ragged-Red Fibers - Fukuhara Disease - MERRF