Table 2 Phenotype reporting recommendations for unprovoked seizures/epilepsy in individuals with newly described multisystem and/or neurodevelopmental Mendelian disorders (PHELIX_Epilepsy version 1.0)

1. Epilepsy syndrome and severity

Strongly recommended

i. Seizure type(s) (per ILAE)

ii.Age at seizure onset

iii. EEG findings (including age(s) at time of study)

iv. Epilepsy syndrome(s) (per ILAE)

v. Findings that support the diagnosis of the epilepsy syndrome(s) (e.g. specific EEG findings)

vi. Seizure frequency at last clinical assessment

vii. Qualifiers of overall epilepsy severity (e.g. severe; treatment-refractory)

Optional, but encouraged

viii. Clarification if EEG data were directly reviewed by members of the study team (versus only report details extracted from medical record)

ix. Number of seizures requiring hospitalization in specific timeframe (e.g. last year)

2. Pharmacological interventions

Strongly recommended

i. Current and past medication name(s)

ii. Perceived impact on seizure control

Optional, but encouraged

iii. Dose

iv. Duration of treatment trial

v. Adverse effects/events due to the intervention

3. Non-pharmacological interventions

Strongly recommended

i. Intervention/procedure details (e.g. ketogenic diet, neurosurgery)

ii. Perceived impact on seizure control

Optional, but encouraged

iii. Adverse effects/events due to the intervention

4. Brain imaging findings

Strongly recommended

i. Brain imaging findings (including age(s) at time of study)

Optional, but encouraged

ii. Clarification if brain imaging data were directly reviewed by members of the study team (versus only report details extracted from medical record)

5. Other

Optional, but encouraged

i. Narrative summary of the progression of the individual’s seizure(s)/epilepsy phenotype over time

ii. Narrative summary of the progression of the individual’s non-epilepsy phenotype over time (e.g. see PHELIX_General guidelines)