An extremely rare genetic variant that affects the maturation, migration, and death of neurons appears to be responsible for about 7% of cases of juvenile myoclonic epilepsy.
Variants of the intestinal-cell kinase gene (ICK) occurred in 12 members of a family affected by the disorder and were confirmed in 22 of 310 additional patients, Julia N. Bailey, PhD , of the University of California, Los Angeles, and her colleagues reported in the March 15 issue of the New England Journal of Medicine .
But among these 34 patients, the variant manifested as different epileptic phenotypes, suggesting genetic pleiotropism, the investigators said.
The investigators drew data from the GENESS (Genetic Epilepsies Studies) consortium, which has study sites in the United States, Mexico, Honduras, Brazil, and Japan. The current study from the databank analyzed information from 334 families with genetic generalized epilepsies. Among these, 310 patients had adolescent-onset myoclonic seizures and polyspike waves, or had a diagnosis of JME.