Adult Phenotype of SYNGAP1 -DEE

Abstract

Background and Objectives: SYNGAP1 variants are associated with rare developmental and epileptic encephalopathies (DEEs). Although SYNGAP1 -related childhood phenotypes are well characterized, the adult phenotype remains ill-defined. We sought to investigate phenotypes and outcomes in adults with SYNGAP1 variants and epilepsy.; Methods: Patients 18 years or older with DEE carrying likely pathogenic and pathogenic (LP/P) SYNGAP1 variants were recruited through physicians' practices and patient organization groups. We used standardized questionnaires to evaluate current seizures, medication use, sleep, gastrointestinal symptoms, pain response, gait, social communication disorder and adaptive skills of patients. We also assessed caregiver burden.; Results: Fourteen unrelated adult patients (median: 21 years, range: 18-65 years) with SYNGAP1 -DEE were identified, 11 with novel and 3 with known LP/P SYNGAP1 de novo variants. One patient with a partial exon 3 deletion had greater daily living skills and social skills than others with single-nucleotide variants. Ten of 14 (71%) patients had drug-resistant seizures, treated with a median of 2 antiseizure medications. All patients (100%) had abnormal pain processing. Sleep disturbances, social communication disorders, and aggressive/self-injurious behaviors were each reported in 86% of patients. Only half of adults could walk with minimal or no assistance. Toileting was normal in 29%, and 71% had constipation. No adult patients could read or understand verbal material at a sixth-grade level or higher. Aggressive/self-injurious behaviors were leading cause of caregiver burden. The oldest patient was aged 65 years; although nonambulant, she had walked independently when younger.; Discussion: Seventy-one percent of patients with SYNGAP1 -DEEs continue to have seizures when adults. Nonseizure comorbidities, especially aggression and self-injurious behaviors, are major management challenges in adults with SYNGAP1 -DEE. Only 50% of adults can ambulate with minimal or no assistance. Almost all adult patients depend on caregivers for many activities of daily living. Prompt diagnostic genetic testing of adults with DEE can inform clinical care and guide outcomes of precision therapies.; Competing Interests: M. Rong reports no disclosures relevant to the manuscript; T.A. Benke receives grant support from NINDS, NIDCD, NIA, Simons Foundation and IRSF. He performs consultancy for AveXis, Ovid, GW Pharmaceuticals, International Rett Syndrome Foundation, Takeda, Taysha, CureGRIN, GRIN Therapeutics, Alcyone, Neurogene, and Marinus; Clinical Trials with Acadia, Ovid, GW Pharmaceuticals, Marinus and RSRT; all remuneration has been made to his department; Q. Zulfiqar Ali reports no disclosures relevant to the manuscript; A. Aledo‐Serrano reports no disclosures relevant to the manuscript; A. Bayat reports no disclosures relevant to the manuscript; A. Rossi reports no disclosures relevant to the manuscript; O. Devinsky receives grant support from NINDS, NIMH, MURI, CDC and NSF. He has equity and/or compensation from the following companies: Ajna Biosciences, Tilray, Receptor Life Sciences, Hitch Biosciences, Tevard Biosciences, Regel Biosciences, Script Biosciences, Actio Biosciences, Empatica, SilverSpike, and California Cannabis Enterprises (CCE). He has received consulting fees from Zogenix, Ultragenyx, BridgeBio, GeneMedicine and Marinus. He holds patents for the use of cannabidiol in treating neurologic disorders which are owned by GW Pharmaceuticals for which he waived financial interests. He holds other patents in molecular biology. He is the managing partner of the PhiFund Ventures; F. Qaiser reports no disclosures relevant to the manuscript; A. Ali reports no disclosures relevant to the manuscript; A. Fasano reports no disclosures relevant to the manuscript; A.S. Bassett reports no disclosures relevant to the manuscript; D.M. Andrade receives grant support from McLaughlin Foundation, UHN Foundation, Dravet Syndrome Foundation. She also received consulting fees from UCB, Biocodex, Paladin, Eisai. Finally, she receives royalties from UpToDate. Go to Neurology.org/NG for full disclosures. (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)