These authors contributed equally to this work.
STXBP1 mutations in early infantile epileptic encephalopathy with suppression-burst pattern
Article first published online: 30 SEP 2010
Wiley Periodicals, Inc. © 2010 International League Against Epilepsy
Volume 51, Issue 12, pages 2397–2405, December 2010
How to Cite
Saitsu, H., Kato, M., Okada, I., Orii, K. E., Higuchi, T., Hoshino, H., Kubota, M., Arai, H., Tagawa, T., Kimura, S., Sudo, A., Miyama, S., Takami, Y., Watanabe, T., Nishimura, A., Nishiyama, K., Miyake, N., Wada, T., Osaka, H., Kondo, N., Hayasaka, K. and Matsumoto, N. (2010), STXBP1 mutations in early infantile epileptic encephalopathy with suppression-burst pattern. Epilepsia, 51: 2397–2405. doi: 10.1111/j.1528-1167.2010.02728.x
- Issue published online: 1 DEC 2010
- Article first published online: 30 SEP 2010
- Accepted August 4, 2010; Early View publication Xxxx Xx, 20Xx.
- West syndrome;
Purpose: De novo STXBP1 mutations have been found in individuals with early infantile epileptic encephalopathy with suppression-burst pattern (EIEE). Our aim was to delineate the clinical spectrum of subjects with STXBP1 mutations, and to examine their biologic aspects.
Methods: STXBP1 was analyzed in 29 and 54 cases of cryptogenic EIEE and West syndrome, respectively, as a second cohort. RNA splicing was analyzed in lymphoblastoid cells from a subject harboring a c.663 + 5G>A mutation. Expression of STXBP1 protein with missense mutations was examined in neuroblastoma2A cells.
Results: A total of seven novel STXBP1 mutations were found in nine EIEE cases, but not in West syndrome. The mutations include two frameshift mutations, three nonsense mutations, a splicing mutation, and a recurrent missense mutation in three unrelated cases. Including our previous data, 10 of 14 individuals (71%) with STXBP1 aberrations had the onset of spasms after 1 month, suggesting relatively later onset of epileptic spasms. Nonsense-mediated mRNA decay associated with abnormal splicing was demonstrated. Transient expression revealed that STXBP1 proteins with missense mutations resulted in degradation in neuroblastoma2A cells.
Discussion: Collectively, STXBP1 aberrations can account for about one-third individuals with EIEE (14 of 43). These genetic and biologic data clearly showed that haploinsufficiency of STXBP1 is the important cause for cryptogenic EIEE.