Table 1.

Salient clinical, genetic diagnosis, neuroimaging and therapeutic response of children with KCNQ2 encephalopathy

	Case 1	Case 2	Case 3	Case 4	Case 5
Age of onset	5 days	Day 1 of life	Day 2 of life	Day 5 of life	Day 2 of life
Age at diagnosis	18 months	3 months	4 yr	5 yr	7 yr
Mutation analysis	Exon 3 c.440C>A (p.Ala147Asp) Heterozygous	Exon 15 Variant: c. 1657C>T (p.Arg553Trp) Heterozygous	Exon 4 c. 620G>A (p.Arg207Gln) Heterozygous	Exon 15 c. 1696G>A (p.Asp566Asn) Heterozygous	Exon 5 c. 788C>T (p.Thr263ile) Heterozygous
ACMG	Missense, LP	Missense, pathogenic	Missense, LP	Missense, LP	Missense, LP
Age of starting SCB	1 month	1.5 months	9 months	5 yr	7 yr
Seizure free since	1 month of age	2.5 months of age	On and off seizures when SCB withdrawn; Seizure free from 2 yr of age after SCB	5 yr	5 yr
Present age	2 yr 10 m	1 yr 8 m	4 yr 10 m	7.5 yr	7.5 yr
Development assessment	Normal (DASII)	Normal (DASII)	Delayed milestones, poor speech (Moderate ID-MISIC)	Speech delay (Moderate ID-MISIC)	Severe ID with mixed quadriparesis (MISIC)
MRI	Normal	Normal	Mild cerebral atrophy	Normal	Mild cerebral atrophy with paucity of white matter
EEG at presentation	Multifocal epileptiform discharges	Multifocal epileptiform discharges	Multifocal epileptiform discharges with suppression burst pattern	Multifocal epileptiform discharges seen	Multifocal epileptiform discharges with suppression burst pattern
Autistic/ADHD	No	No	Hyperactivity, Autistic behaviour, poor eye contact	Moderate ID with ADHD	Because of severe ID, ASD diagnosis could not be clearly done

ID-Intellectual disability, ADHD-Attention deficit hyperactivity disorder, EEG- Electroencephalography, ACMG-American college of Med genetics classification, SCB-Sodium channel blockers, LP-likely pathogenic, DASII-(Developmental assessment scale for Indian Infants) in children up to 3 years and MISIC-Malin’s intelligence scale of Indian Chidren (>3 yrs)