Table 1.
Clinical features of KCNC1 patients
| This publication | This publication | This publication | This publication | This publication | MEAK patients13, 14, 15 | Poirier et al. 2017 | |
|---|---|---|---|---|---|---|---|
| Patient | Patient 1 | Patient 2 | Patient 3 | Patient 4 | Patient 5 | 22 cases | 3 cases |
| Variant | c.623G > A, p.Cys208Tyr | c.1196C > T, p.Thr399Met | c.1262C > T, p.Ala421Val | c.1262C > T, p.Ala421Val | c.1262C > T, p.Ala421Val | c.959G > A, p.Arg320His | c.1015C > T, p.Arg339* |
| Inheritance | De novo | De novo | De novo | De novo | De novo | De novo (14), 3 families (8) | Paternal |
| Age at onset (current age) | 2 years (23 years) | 1–2 years (18 years) | 5 months (5 years) | 3 weeks (2 years) | 5 months (2 years) | 3–15 years | 1–2 years |
| First sign | Myoclonus or "tremor" | Developmental delay | Myoclonic seizures | Febrile seizures | Myoclonic seizures | Myoclonus or "tremor" | Developmental delay |
| Seizures | No | No | Tonic‐clonic, focal onset impaired awareness, myoclonic, generalized | Myoclonic absence, myoclonic, absence | Myoclonic absence, absence, generalized | Tonic‐clonic, myoclonic, generalized | No |
| Action‐induced Myoclonus | Mild, nonprogressive | No | No | No | No | Severe, progressive | No |
| EEG | Normal | Normal | Normal background, irregular spike‐wave activity with polyspikes and rhythmic generalized 2 Hz spike‐waves | Normal background activity, generalized 2–3 Hz spike‐wave discharges | Normal background, generalized 2–4 Hz rhythmic slow waves and sometimes spike‐waves | Normal background, generalized polyspike, polyspike‐wave and spike‐wave (13), unknown (9) | Normal |
| Brain MRI | Normal | Normal | Normal | Normal | Normal | Global symmetrical cerebellar atrophy (13) unknown (9) | Normal |
| Ataxia | No | No | Mild, so far nonprogressive | Balancing difficulties possible | No | Progressive | No |
| Developmental delay | No | Yes | Yes | Yes | Yes | Mild (2), no (20) | Yes |
| Cognitive Decline | Possible memory deficits (MOCA 28/30) | No | No | No | No | Yes (11), possible (2), no (7) | No |
| Dysmorphism | No | Hypertelorism, long palpebral fissures, broad nose, large ears, diastema, small chin | No | No | No | No | Prognathism, protruding ears, short philtrum, fetal pads, epicanthal folds, ptosis |
| Others | Dystonia, scoliosis | Frequent diarrhea and vomiting | Mild muscular hypotonia | Mild muscular hypotonia | Cannot walk yet | Wheelchair‐dependent (11) | Clinodactyly of the fifth finger (1) |