Adult Phenotype of <i>SYNGAP1</i> -DEE
Marlene Rong, Tim A. Benke, Quratulain Zulfiqar Ali, Ángel Aledo‐Serrano, Allan Bayat, Alessandra Rossi, Orrin Devinsky, Farah Qaiser, Anum Ali, Alfonso Fasano, Anne S. Bassett, Danielle M. Andrade
Abstract
<h3>Background and Objectives</h3> <i>SYNGAP1</i> variants are associated with rare developmental and epileptic encephalopathies (DEEs). Although <i>SYNGAP1</i>-related childhood phenotypes are well characterized, the adult phenotype remains ill-defined. We sought to investigate phenotypes and outcomes in adults with <i>SYNGAP1</i> variants and epilepsy. <h3>Methods</h3> Patients 18 years or older with DEE carrying likely pathogenic and pathogenic (LP/P) <i>SYNGAP1</i> variants were recruited through physicians9 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. <h3>Results</h3> Fourteen unrelated adult patients (median: 21 years, range: 18–65 years) with <i>SYNGAP1</i>-DEE were identified, 11 with novel and 3 with known LP/P <i>SYNGAP1</i> 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. <h3>Discussion</h3> Seventy-one percent of patients with <i>SYNGAP1</i>-DEEs continue to have seizures when adults. Nonseizure comorbidities, especially aggression and self-injurious behaviors, are major management challenges in adults with <i>SYNGAP1</i>-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.