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Meta-Analysis
. 2017 Nov 2;101(5):664-685.
doi: 10.1016/j.ajhg.2017.09.008.

High Rate of Recurrent De Novo Mutations in Developmental and Epileptic Encephalopathies

Fadi F Hamdan  1 Candace T Myers  2 Patrick Cossette  3 Philippe Lemay  1 Dan Spiegelman  4 Alexandre Dionne Laporte  4 Christina Nassif  1 Ousmane Diallo  4 Jean Monlong  5 Maxime Cadieux-Dion  6 Sylvia Dobrzeniecka  7 Caroline Meloche  7 Kyle Retterer  8 Megan T Cho  8 Jill A Rosenfeld  9 Weimin Bi  10 Christine Massicotte  1 Marguerite Miguet  1 Ledia Brunga  11 Brigid M Regan  12 Kelly Mo  12 Cory Tam  12 Amy Schneider  13 Georgie Hollingsworth  13 Deciphering Developmental Disorders Study  14 David R FitzPatrick  15 Alan Donaldson  16 Natalie Canham  17 Edward Blair  18 Bronwyn Kerr  19 Andrew E Fry  20 Rhys H Thomas  21 Joss Shelagh  22 Jane A Hurst  23 Helen Brittain  23 Moira Blyth  24 Robert Roger Lebel  25 Erica H Gerkes  26 Laura Davis-Keppen  27 Quinn Stein  28 Wendy K Chung  29 Sara J Dorison  30 Paul J Benke  31 Emily Fassi  32 Nicole Corsten-Janssen  26 Erik-Jan Kamsteeg  33 Frederic T Mau-Them  34 Ange-Line Bruel  34 Alain Verloes  35 Katrin Õunap  36 Monica H Wojcik  37 Dara V F Albert  38 Sunita Venkateswaran  39 Tyson Ware  40 Dean Jones  41 Yu-Chi Liu  42 Shekeeb S Mohammad  43 Peyman Bizargity  9 Carlos A Bacino  44 Vincenzo Leuzzi  45 Simone Martinelli  46 Bruno Dallapiccola  47 Marco Tartaglia  47 Lubov Blumkin  48 Klaas J Wierenga  49 Gabriela Purcarin  49 James J O'Byrne  50 Sylvia Stockler  50 Anna Lehman  51 Boris Keren  52 Marie-Christine Nougues  53 Cyril Mignot  52 Stéphane Auvin  54 Caroline Nava  52 Susan M Hiatt  55 Martina Bebin  56 Yunru Shao  9 Fernando Scaglia  9 Seema R Lalani  9 Richard E Frye  57 Imad T Jarjour  58 Stéphanie Jacques  59 Renee-Myriam Boucher  60 Emilie Riou  61 Myriam Srour  62 Lionel Carmant  63 Anne Lortie  64 Philippe Major  64 Paola Diadori  64 François Dubeau  4 Guy D'Anjou  64 Guillaume Bourque  5 Samuel F Berkovic  13 Lynette G Sadleir  65 Philippe M Campeau  66 Zoha Kibar  67 Ronald G Lafrenière  7 Simon L Girard  68 Saadet Mercimek-Mahmutoglu  69 Cyrus Boelman  70 Guy A Rouleau  4 Ingrid E Scheffer  71 Heather C Mefford  2 Danielle M Andrade  12 Elsa Rossignol  63 Berge A Minassian  72 Jacques L Michaud  73
Affiliations
Meta-Analysis

High Rate of Recurrent De Novo Mutations in Developmental and Epileptic Encephalopathies

Fadi F Hamdan et al. Am J Hum Genet. .

Abstract

Developmental and epileptic encephalopathy (DEE) is a group of conditions characterized by the co-occurrence of epilepsy and intellectual disability (ID), typically with developmental plateauing or regression associated with frequent epileptiform activity. The cause of DEE remains unknown in the majority of cases. We performed whole-genome sequencing (WGS) in 197 individuals with unexplained DEE and pharmaco-resistant seizures and in their unaffected parents. We focused our attention on de novo mutations (DNMs) and identified candidate genes containing such variants. We sought to identify additional subjects with DNMs in these genes by performing targeted sequencing in another series of individuals with DEE and by mining various sequencing datasets. We also performed meta-analyses to document enrichment of DNMs in candidate genes by leveraging our WGS dataset with those of several DEE and ID series. By combining these strategies, we were able to provide a causal link between DEE and the following genes: NTRK2, GABRB2, CLTC, DHDDS, NUS1, RAB11A, GABBR2, and SNAP25. Overall, we established a molecular diagnosis in 63/197 (32%) individuals in our WGS series. The main cause of DEE in these individuals was de novo point mutations (53/63 solved cases), followed by inherited mutations (6/63 solved cases) and de novo CNVs (4/63 solved cases). De novo missense variants explained a larger proportion of individuals in our series than in other series that were primarily ascertained because of ID. Moreover, these DNMs were more frequently recurrent than those identified in ID series. These observations indicate that the genetic landscape of DEE might be different from that of ID without epilepsy.

Keywords: CLTC; DHDDS; GABBR2; GABRB2; NTRK2; NUS1; RAB11; SNAP25; epileptic encephalopathy.

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Figures

Figure 1
Figure 1
Localization of De Novo Variants in Protein Domains Encoded by Genes of Interest GABRB2 (A), CLTC (B), NUS1 (C), NTRK2 (D), and DHDDS, SNAP25, GABBR2, and RAB11A (E). Recurrent de novo variants are in italics and red font. The transmembrane domains of GABRB2 and GABBR2 are labeled 1–4 and 1–7, respectively. Abbreviations are as follows: TM, transmembrane domain; TD, trimerization domain; SP, signal peptide; LRRNT, leucine-rich repeat N-terminal domain; LRR, leucine-rich repeat; LRRCT, leucine-rich repeat C-terminal domain; IGC2, immunoglobulin C-2 type 1 domain; IGC2-2, immunoglobulin C-2 type 2 domain; Shc, SHC1 interaction domain; IPP, isopentenyl diphosphate binding site; CD, catalytic domain; FPP, farnesyl diphosphate binding site; SW, switch domain; and CC, prenylation residue.

Comment in

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