Unverricht-Lundborg Disease (EPM1) is a neurodegenerative disease with onset during the pediatric period.


Chromosome locus: 21q22.3

Gene: CSTB (pathogenic variants include dodecamer repeat expansion)

Protein affected: cystatin B (a cysteine protease inhibitor)


Inheritance: autosomal recessive


The onset is between 6 and 15 years of age.


Clinical features:

(1) tonic-clonic epileptic seizures.

(2) stimulus sensitive myoclonus (mycoclonic jerks)

(3) ataxia and incoordination

(4) intentional tremor

(5) dysarthria

(6) emotional lability and/or depression

(7) intellectual decline that is usually mild


MRI of the brain is normal.


The EEG is always abnormal and may show photosensitive paroxysms.


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