. 2019 Jul 22;4(3):504–510. doi: 10.1002/epi4.12350

Table 1.

Clinical and etiology findings in epidemiological cohort of infantile DEEs

Subject number/Gender age at last review	Onset age of seizures Syndrome	Clinical details	Etiology
1/ F 2 y4 mo	8 mo West syndrome	Epileptic spasms Profound GDD EEG: Hypsarrhythmia MRI: Moderate lissencephaly, gradient: posterior more severe than anterior	Lissencephaly Miller‐Dieker 17p13.3 microdeletion
2/ M 6 y1 mo	7 mo West syndrome	Spasms, focal motor seizures Profound GDD EEG: Hypsarrhythmia MRI: Moderate lissencephaly, gradient: posterior more severe than anterior, pontine hypoplasia	Lissencephaly 17p mosaic microduplication
3/ M 2 y6 mo	20 mo DEE	Unifocal seizures Regression with seizures. Surgery curative. Mild language delay EEG: Left frontotemporal IEDs MRI: Segmental focal cortical dysplasia, subependymal nodules	Focal cortical dysplasia Genetic testing not done
4/ F 4 y4 mo	2 wk DEE	Focal tonic, FIAS Plateau with seizures. Mild language delay. EEG: Multifocal IEDs. MRI: Multifocal tubers.	Tuberous sclerosis complex Genetic testing not done
5/ F 4 y1 mo	5 mo West syndrome	Spasms, Focal motor seizures Hemiplegia, regression with spasms EEG: Hypsarrhythmia; unifocal centro‐temporal spike IEDs MRI: Antenatal venous infarction with multicystic encephalomalacia	Antenatal clastic vascular Genetic testing not done
6/ F 2 y3 mo	3 d EIMFS	Focal seizures, migrating focal seizures Mild GDD EEG: Ictal rhythms migrating between hemispheres; 6 mo & 13 mo normal MRI: Normal	*KCNQ2* c.637C>T p.Arg213Trp^a de novo Pathogenic^b
7/ F 2 y1 mo	2 mo West syndrome	Focal tonic seizures, spasms, multifocal myoclonia Acquired microcephaly, dyskinesia, profound GDD EEG: Hypsarrhythmia; multifocal discharges MRI: Acquired moderate cerebral atrophy	*KCNQ2* c.593G>A p.Arg198Gln^a de novo Pathogenic^b
8/ M 19 mo	4 wk DEE	Tonic‐clonic seizures, focal tonic seizures Severe GDD EEG: Bilateral occipital IEDs MRI: Hypoplastic corpus callosum	*ARX* c.1449‐1 G>C p.Leu484*^c Pathogenic^b
9/ F 5 y4 mo	6 mo DEE	Tonic‐clonic seizures, FBTC Language delay EEG: 11 mo‐Ictal rhythm midline to frontocentral regions; 2 y1 mo‐GSW, PSW MRI: Normal	*SCN8A* c. 5009T>G p.Met1670Arg^c Uncertain significance^b (de novo status unproven)
10/ F 5 y10 mo	6 mo DEE	Absence with eyelid myoclonia, absence, eyelid myoclonia, myoclonic jerks, tonic‐clonic seizures, NCSE Profound GDD, visual impairment EEG: Marked photosensitivity, 3‐4Hz GSW, PSW, myoclonic‐atonic seizure MRI: Normal	*DHDDS* c.632G>A p.Arg211Gln^a de novo Pathogenic^b
11/ M deceased 17 d	5 d EME	Myoclonic jerks Decreased activity, poor feeding, jitteriness EEG: Burst suppression MRI: Normal	*GABRB2* c.851C>A p.Thr284Lys^c de novo Likely pathogenic^b
12/ F 8 y3 mo	7 mo DEE	Febrile seizures, vibratory tonic seizures, tonic‐clonic seizures, absence Profound GDD, hypotonia, truncal ataxia, ambulating with walker at 4 y EEG: GSW, multifocal discharges, PSW MRI: Normal, no cerebellar atrophy	*CACNA1G* c.2727G>C p.Leu909Phe^c Likely pathogenic (gain of function in vitro [unpublished]; de novo status unproven)^b
13/ F 4 y7 mo	5 mo West syndrome	Spasms Remission at 8 mo, severe ID and GDD, seizure free without medication EEG: Hypsarrhythmia MRI: Normal	*SNAP25* c. 526C>T p.Arg176Cys^c Uncertain significance^b (de novo status unproven)
14/ F 4 y10 mo	13 mo DEE	Myoclonic jerks; Focal motor seizures at 2 y Hypotonia, delayed visual maturation, severe ID and GDD EEG: Multifocal discharges, normal at 23 mo MRI: Normal	Unknown Candidate gene: FAT1 c.8626G>C p.Asp2876His^c c.7655A>G p.Glu2552Gly^c Uncertain significance^b
15/ M 4 y6 mo	9 mo West syndrome	Spasms Developmental plateau with spasms EEG: Hypsarrhythmia MRI: Normal	Unknown
16/ F 6 y9 mo	10 mo DEE	Focal tonic seizures, tonic‐clonic seizures, FIAS Specific learning difficulties EEG: 15 mo‐normal; 21 mo‐occipital ictal rhythm; 22 mo‐occipital IEDs; 4 y‐normal MRI: Normal	Unknown

Abbreviations: BS, burst suppression; DEE, developmental and epileptic encephalopathy; EIMFS, epilepsy of infancy with migrating focal seizures; EME, early myoclonic encephalopathy; FBTC, focal to bilateral tonic‐clonic seizure; FIAS, focal impaired awareness seizure; GDD, global developmental delay; GSW, generalized spike‐wave; ID, intellectual disability; IEDs, interictal epileptiform discharges; MFDs, multifocal discharges; NCSE, nonconvulsive status epilepticus; PSW, polyspike‐wave.

previously published variant.

ACMG classification.

Novel variant.