Epilepsy

Epilepsy is a neurological disorder caused by recurring disturbances in the normal electrical functions of the brain. These irregular bursts of electrical energy cause seizures and can affect a person's level of awareness, muscle control, and sensations for a short period of time.

Epilepsy affects more than two million people in the US – approximately one-third are children under the age of 18.²⁸ Twenty different forms of the disorder have been identified.²⁸ The majority of all cases are idiopathic and some may be hereditary as well.²⁸ About 20 epileptic medications are available, while surgery, diet, and vagus nerve stimulation are also treatment options for some patients with epilepsy.²⁸

• Progressive myoclonus epilepsy of the Unverricht-Lundborg type (EPM1) is an inherited form of epilepsy for which there is a diagnostic DNA test. EPM1, or Baltic Myoclonus, is an autosomal recessive disease causing myoclonus, epilepsy, ataxia, and in some cases, intellectual decline.²³ Patients usually present with symptoms in late childhood through teen years.²³ EEG is typically abnormal, demonstrating high-voltage spike-and-wave and polyspike-and-wave paroxysms which are symmetric and generalized.²³ Routine blood tests are normal.²³ The most common EPM1 mutation is caused by an expansion of a sequence of 12 nucleotides, which is abnormally repeated as a unit in the cystatin B gene.²³ In the differential diagnosis, EPM1 can have a similar clinical presentation to MERRF.
  
• Tuberous Sclerosis Complex
  Tuberous Sclerosis is a dominantly inherited, multisystemic, genetic disease that affects approximately one in 5,800 live births.⁴³ Mutations in two genes, TSC1 and TSC2, have been linked to TSC.⁴⁴ This disease is characterized by hamartomas in various parts of the body, including the skin, brain, heart, lung and kidney. Onset is usually in early childhood and penetrance is considered to be 100%. Approximately 66% of disease-causing mutations are considered to be sporadic.^44,45
  
  Clinical features of TSC include: abnormalities of skin, such as hypomelanotic macules, facial angiofibromas, and shagreen patches; abnormalities of the central nervous system, such as seizures, developmental delay, as well as subependymal glial nodules and cortical or subcortical tubers; renal lesions, such as angiomyolipomas and epithelial cysts; cardiac rhabdomyomas; lymphangiomyomatosis of the lung; and hamartomas in the eye.^43,44,45

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