No evidence of a role for cystatin B gene in juvenile myoclonic epilepsy

Genetic factors play a major role in the etiology of juvenile myoclonic epilepsy (JME), a common form of idiopathic generalized epilepsy, but so far, genesrelated to JME remain largely unknown. JME shares electroclinical features withUnverricht-Lundborg disease (progressive myoclonic epilepsy type 1; EPM1), a formof progressive myoclonus epilepsy characterized by myoclonus, epilepsy, andgradual neurologic deterioration. EPM1 is caused by mutations in the gene thatcodes for cystatin B (CSTB), an inhibitor of cysteine protease. In the presentstudy, we wished to investigate the role of the CSTB gene in patients with JME.Fifty-seven unrelated patients (35 women; mean age ± standard deviation [SD],24.1 ± 7.7; mean age ± SD at onset, 15.3 ± 2.4) with JME were enrolled.Twenty-three of 57 patients were the probands of families with JME. The moleculardiagnosis was carried out to identify the common dodecamer repeat expansionmutation or other disease-causing mutations in the CSTB gene. The molecularanalysis did not depict mutations in any of the 57 patients with JME. Our studydid not support a role for the CSTB gene in patients with familial or sporadicJME.