The Gait Outcomes Assessment List (GOAL) can discriminate between Gross Motor Function Classification System levels. The GOAL correlates with standard functional assessments and gait analysis. Used with gait analysis, the GOAL provides comprehensive assessment across all International Classification of Functioning, Disability and Health domains.

Background and ObjectivesThe genetic developmental and epileptic encephalopathies (DEEs) comprise a large group of severe epilepsy syndromes, with a wide phenotypic spectrum. Currently, the rates of convulsive status epilepticus (CSE), non-convulsive status epilepticus (NCSE) and sudden unexplained death in epilepsy (SUDEP) in these diseases are not well understood. We aimed to describe the proportions of patients with frequently observed genetic DEEs who developed CSE, NCSE, mortality and SUDEP. Understanding the risks of these serious presentations in each genetic DEE will enable earlier diagnosis and appropriate management.MethodsIn this retrospective analysis of patients with a genetic DEE, we estimated the proportions with CSE, NCSE and SUDEP and the overall and SUDEP-specific mortality rates for each genetic diagnosis. We included patients with a pathogenic variant in the following genes:SCN1A, SCN2A, SCN8A, SYNGAP1, NEXMIF, CHD2, PCDH19, STXBP1, GRIN2A, KCNT1, KCNQ2and Angelman syndrome (AS).ResultsThe cohort comprised 510 individuals with a genetic DEE; in whom we observed CSE in 47% and NCSE in 19%. The highest proportion of CSE occurred in patients withSCN1A-associated DEEs, including 181/203 (89%; 95%CI 84-93%) patients with Dravet syndrome and 8/15 (53%; 95%CI 27-79%) non-DravetSCN1A-DEEs. CSE was also notable in patients with pathogenic variants inKCNT1(6/10; 60%; 95%CI 26-88%) andSCN2A(8/15; 53%; 95%CI 27-79%). NCSE was common in patients with non-DravetSCN1A-DEEs (8/15; 53%; 95%CI 27-79%) and was notable in patients withCHD2-DEEs(6/14; 43%; 95%CI 18-71%) and AS (6/19; 32%; 95%CI 13-57%). There were 42/510 (8%) deaths amongst the cohort, producing a mortality rate of 6.1 per 1000 person years (95% CI 4.4 – 8.3). SUDEP cases accounted for 20/42 (48%) deaths. Four genes were associated with SUDEP:SCN1A, SCN2A, SCN8AandSTXBP1.The estimated SUDEP rate was 2.9 per 1000 person years (95% CI 1.7 – 4.5).DiscussionWe showed that proportions of patients with CSE, NCSE and SUDEP differ for commonly encountered genetic DEEs. The estimates for each genetic DEE studied will inform early diagnosis and management of status epilepticus and SUDEP and inform disease-specific counselling for patients and families in this high-risk group of conditions.