Germline De Novo Mutations in GNB1 Cause Severe Neurodevelopmental Disability, Hypotonia, and Seizures

Slavé Petrovski, Sébastien Küry, Candace T. Myers, Kwame Anyane-Yeboa, Benjamin Cogné, Martin Bialer, Fan Xia, Parisa Hemati, James Riviello, Michele Mehaffey, Thomas Besnard, Emily Becraft, Alexandrea Wadley, Anya Revah Politi, Sophie Colombo, Xiaolin Zhu, Zhong Ren, Ian Andrews, Tracy Dudding-Byth, Amy L. Schneider, Geoffrey Wallace, University of Washington Center for Mendelian Genomics, Aaron B.I. Rosen, Susan Schelley, Gregory M. Enns, Pierre Corre, Joline Dalton, Sandra Mercier, Xénia Latypova, Sébastien Schmitt, Edwin Guzman, Christine Moore, Louise Bier, Erin L. Heinzen, Peter Karachunski, Natasha Shur, Theresa Grebe, Alice Basinger, Joanne M. Nguyen, Stéphane Bézieau, Klaas Wierenga, Jonathan A. Bernstein, Ingrid E. Scheffer, Jill A. Rosenfeld, Heather C. Mefford, Bertrand Isidor, David B. Goldstein

Whole-exome sequencing of 13 individuals with developmental delay commonly accompanied by abnormal muscle tone and seizures identified de novo missense mutations enriched within a sub-region of GNB1, a gene encoding the guanine nucleotide-binding protein subunit beta-1, Gβ. These 13 individuals were identified among a base of 5,855 individuals recruited for various undiagnosed genetic disorders. The probability of observing 13 or more de novo mutations by chance among 5,855 individuals is very low (p = 7.1 × 10(-21)), implicating GNB1 as a genome-wide-significant disease-associated gene. The majority of these 13 mutations affect known Gβ binding sites, which suggests that a likely disease mechanism is through the disruption of the protein interface required for Gα-Gβγ interaction (resulting in a constitutively active Gβγ) or through the disruption of residues relevant for interaction between Gβγ and certain downstream effectors (resulting in reduced interaction with the effectors). Strikingly, 8 of the 13 individuals recruited here for a neurodevelopmental disorder have a germline de novo GNB1 mutation that overlaps a set of five recurrent somatic tumor mutations for which recent functional studies demonstrated a gain-of-function effect due to constitutive activation of G protein downstream signaling cascades for some of the affected residues.