De Novo Truncating Mutation of TRIM8 Causes Early-Onset Epileptic Encephalopathy

Yasunari Sakai, Ryoko Fukai, Yuki Matsushita, Noriko Miyake, Hirotomo Saitsu, Satoshi Akamine, Michiko Torio, Momoko Sasazuki, Yoshito Ishizaki, Masafumi Sanefuji, Hiroyuki Torisu, Chad A. Shaw, Naomichi Matsumoto, Toshiro Hara

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22 Citations (Scopus)


Background: Early-onset epileptic encephalopathy (EOEE) is a heterogeneous group of neurodevelopmental disorders characterised by infantile-onset intractable epilepsy and unfavourable developmental outcomes. Hundreds of mutations have been reported to cause EOEE; however, little is known about the clinical features of individuals with rare variants. Case report and methods: We present a 10-year-old boy with severe developmental delay. He started experiencing recurrent focal seizures at 2 months old. Serial electroencephalograms persistently detected epileptiform discharges from the left hemisphere. Whole-exome sequencing and array-comparative genome hybridization were performed to search for de novo variations. Two-week-old C57Bl/6 mice were used for immunofluorescence studies. Results: This case had a paternally inherited, 0.2-Mb duplication at chromosome 22q11.22. The whole-exome sequencing identified a de novo truncating mutation of tripartite motif containing 8 (TRIM8) (NM_030912:c.1099_1100insG:p.C367fs), one of the epileptic encephalopathy-associated genes. We verified that the murine homologues of these genes are expressed in the postnatal mouse brain. Conclusion: This is the second case of EOEE caused by a de novo truncating mutation of TRIM8. Further studies are required to determine the functional roles of TRIM8 in the postnatal development of the human brain and its functional relationships with other EOEE-associated genes.

Original languageEnglish
Pages (from-to)235-240
Number of pages6
JournalAnnals of Human Genetics
Issue number4
Publication statusPublished - Jul 1 2016

All Science Journal Classification (ASJC) codes

  • Genetics
  • Genetics(clinical)


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