Biallelic SZT2 mutations cause infantile encephalopathy with epilepsy and dysmorphic corpus callosum

Lina Basel-Vanagaite, Tova Hershkovitz, Eli Heyman, Miquel Raspall-Chaure, Naseebullah Kakar, Pola Smirin-Yosef, Marta Vila-Pueyo, Liora Kornreich, Holger Thiele, Harald Bode, Irina Lagovsky, Dvir Dahary, Ami Haviv, Monika Weisz Hubshman, Metsada Pasmanik-Chor, Peter Nürnberg, Doron Gothelf, Christian Kubisch, Mordechai Shohat, Alfons MacayaGuntram Borck

Research output: Contribution to journalArticleResearchpeer-review

45 Citations (Scopus)

Abstract

Epileptic encephalopathies are genetically heterogeneous severe disorders in which epileptic activity contributes to neurological deterioration. We studied two unrelated children presenting with a distinctive early-onset epileptic encephalopathy characterized by refractory epilepsy and absent developmental milestones, as well as thick and short corpus callosum and persistent cavum septum pellucidum on brain MRI. Using whole-exome sequencing, we identified biallelic mutations in seizure threshold 2 (SZT2) in both affected children. The causative mutations include a homozygous nonsense mutation and a nonsense mutation together with an exonic splice-site mutation in a compound-heterozygous state. The latter mutation leads to exon skipping and premature termination of translation, as shown by RT-PCR in blood RNA of the affected boy. Thus, all three mutations are predicted to result in nonsense-mediated mRNA decay and/or premature protein truncation and thereby loss of SZT2 function. Although the molecular role of the peroxisomal protein SZT2 in neuronal excitability and brain development remains to be defined, Szt2 has been shown to influence seizure threshold and epileptogenesis in mice, consistent with our findings in humans. We conclude that mutations in SZT2 cause a severe type of autosomal-recessive infantile encephalopathy with intractable seizures and distinct neuroradiological anomalies. © 2013 The American Society of Human Genetics.
Original languageEnglish
Pages (from-to)524-529
JournalAmerican Journal of Human Genetics
Volume93
Issue number3
DOIs
Publication statusPublished - 5 Sep 2013

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