Table 1.
Main clinical features of patients
| Patient | 1 | 2 | 3 |
|---|---|---|---|
| Age at last follow up | 5y | 4y 4mo | unknown |
| Gene; variant | KCNQ2; c.949G > A, p.A317T | KCNQ2; c.952C > G, p.L318V | KCNQ3; c.1066C > T, p.A356T |
| Early development | Delayed motor milestones | Global DD | Delayed speech development |
| Regression | Yes. Complex babble at 8 mo, nonverbal by 5y | Yes, after seizure onset, resulting in language delay and impairment of fine motor skills | Not reported |
| Neurobehavioral problems | Severe ASD, extremely hyperactive, and impulsive | Not reported | Abnormal repetitive mannerisms, bimanual synkinesia |
| Current level of functioning | Severe ID | Not reported | Moderate global DD |
| Seizures | No | Epileptic spasms (5mo), Controlled with ACTH at 10mo | Not reported |
| EEG | Awake and sleep EEG at 10mo normal | HS between 5 to 10mo; Rolandic discharges at 1y10mo; SWAS at 2y3mo | Not reported |
| Other | Corpus callosum agenesis on MRI | Poor motor coordination | |
| Reference | This study | 33 (case 6) | 34 (patient DDD4K. 02558) |
Abbreviations: ASD: autism spectrum disorder; ACTH: adrenocorticotrophic hormone; DD: Developmental delay; HS: hypsarrhythmia; ID: intellectual disability; mo: months; SWAS: Spike and wave activation in sleep; y: years.