Adult-onset autosomal dominant myoclonic epilepsy: report of a family with an overlooked epileptic syndrome.
OBJECTIVE
Myoclonic epilepsy is a common epileptic syndrome with high genetic contribution. We described a pedigree in which 10 individuals presented with a non-progressive, adult-onset myoclonic epilepsy.


METHODS
The pedigree was constructed and analyzed. Six affected members were studied with clinical grounds, mental status, neurophysiology, video-electroencephalographic (EEG), brain magnetic resonance imaging (MRI) and mutational analysis of GABRA1 (GABRA1A, which endoces the alpha1 subunit of the gamma-aminobutyric acid receptor subtype A). Clinical and EEG data were collected from six unaffected members.


RESULTS
Autosomal dominant hereditary was shown. The age of seizure onset was approximately 40. All the individuals had myoclonic seizures and a normal cognitive level. Bilateral symmetric jerks of the shoulders, arms or legs featured the myoclonic seizure. Ictally, the consciousness was not affected. The ictal EEG demonstrated bilateral spikes-and-waves. The occurrence of myoclonic seizures was not associated with sleepiness. Rare generalized tonic-clonic seizures occurred in two individuals. No absence or accompanying involuntary movements were observed. A lower dose of valproic acid (200-500 mg/D) (clonazepam 0.5 mg/D in a patient) was required to stop the myoclonic seizures.


CONCLUSIONS
The clinical features of late adult-onset autosomal dominant myoclonic epilepsy are similar to juvenile myoclonic epilepsy (JME), which is a common generalized epileptic syndrome with a significant hereditary component. But the age of onset, rare association of other seizure patterns, and non-relation of seizure onset to sleepiness suggest that this may be a distinct familial epileptic syndrome different from recognized familial myoclonic epilepsies.
Hsin
Yue-Loong
YL
Department of Neurology, Buddhist Tzu Chi General Hospital, and Institute of Medical Sciences, Buddhist Tzu Chi University, Hualien, Taiwan.
Chuang
Min-Fei
MF
Shyu
Woei-Cherng
WC
Lin
Chih-Yuan
CY
Chen
Yen-Ho
YH
Harnod
Tomor
T
D000328:Adult; D017668:Age of Onset; D000368:Aged; D000927:Anticonvulsants / Q000008:administration & dosage; D004569:Electroencephalography; D004831:Epilepsies, Myoclonic / Q000188:drug therapy / Q000235:genetics*; D005260:Female; D030342:Genetic Diseases, Inborn / Q000175:diagnosis*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D011963:Receptors, GABA-A / Q000235:genetics*; D014635:Valproic Acid / Q000008:administration & dosage; D014741:Video Recording
D000927:Anticonvulsants; C546240:GABRA1 protein, human; D011963:Receptors, GABA-A; D014635:Valproic Acid