September 22, 2019  |  

Expansions of intronic TTTCA and TTTTA repeats in benign adult familial myoclonic epilepsy.

Authors: Ishiura, Hiroyuki and Doi, Koichiro and Mitsui, Jun and Yoshimura, Jun and Matsukawa, Miho Kawabe and Fujiyama, Asao and Toyoshima, Yasuko and Kakita, Akiyoshi and Takahashi, Hitoshi and Suzuki, Yutaka and Sugano, Sumio and Qu, Wei and Ichikawa, Kazuki and Yurino, Hideaki and Higasa, Koichiro and Shibata, Shota and Mitsue, Aki and Tanaka, Masaki and Ichikawa, Yaeko and Takahashi, Yuji and Date, Hidetoshi and Matsukawa, Takashi and Kanda, Junko and Nakamoto, Fumiko Kusunoki and Higashihara, Mana and Abe, Koji and Koike, Ryoko and Sasagawa, Mutsuo and Kuroha, Yasuko and Hasegawa, Naoya and Kanesawa, Norio and Kondo, Takayuki and Hitomi, Takefumi and Tada, Masayoshi and Takano, Hiroki and Saito, Yutaka and Sanpei, Kazuhiro and Onodera, Osamu and Nishizawa, Masatoyo and Nakamura, Masayuki and Yasuda, Takeshi and Sakiyama, Yoshio and Otsuka, Mieko and Ueki, Akira and Kaida, Ken-Ichi and Shimizu, Jun and Hanajima, Ritsuko and Hayashi, Toshihiro and Terao, Yasuo and Inomata-Terada, Satomi and Hamada, Masashi and Shirota, Yuichiro and Kubota, Akatsuki and Ugawa, Yoshikazu and Koh, Kishin and Takiyama, Yoshihisa and Ohsawa-Yoshida, Natsumi and Ishiura, Shoichi and Yamasaki, Ryo and Tamaoka, Akira and Akiyama, Hiroshi and Otsuki, Taisuke and Sano, Akira and Ikeda, Akio and Goto, Jun and Morishita, Shinichi and Tsuji, Shoji

Epilepsy is a common neurological disorder, and mutations in genes encoding ion channels or neurotransmitter receptors are frequent causes of monogenic forms of epilepsy. Here we show that abnormal expansions of TTTCA and TTTTA repeats in intron 4 of SAMD12 cause benign adult familial myoclonic epilepsy (BAFME). Single-molecule, real-time sequencing of BAC clones and nanopore sequencing of genomic DNA identified two repeat configurations in SAMD12. Intriguingly, in two families with a clinical diagnosis of BAFME in which no repeat expansions in SAMD12 were observed, we identified similar expansions of TTTCA and TTTTA repeats in introns of TNRC6A and RAPGEF2, indicating that expansions of the same repeat motifs are involved in the pathogenesis of BAFME regardless of the genes in which the expanded repeats are located. This discovery that expansions of noncoding repeats lead to neuronal dysfunction responsible for myoclonic tremor and epilepsy extends the understanding of diseases with such repeat expansion.

Journal: Nature genetics
DOI: 10.1038/s41588-018-0067-2
Year: 2018

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