Table 1 Clinical features of patients with KCNB1 mutations.
From: De novo KCNB1 mutations in infantile epilepsy inhibit repetitive neuronal firing
Patient 1 | Patient 2 | Case ID9* | Case 2* | Case 3* | |
|---|---|---|---|---|---|
Age | 4 yr | 7 yr | 9 yr | 7 yr | 5 yr |
Sex | Male | Male | Female | Male | Female |
Mutation | c.1201G>A (p.G401R) | c.916C>T (p.R306C) | c.1041C>A (p.S347R) | c.1135G>A (p.G379R) | c.1121C>T (p.T374I) |
Initial symptoms | Developmental delay | Developmental delay | Developmental delay | Developmental delay | N.D. |
Age at seizure onset | 1 yr 5 mo | 1 yr | 4 yr | 8 mo | 0 yr |
Seizure types | Clonic at 1 yr 5 mo, focal with jerking of mouth | Spasms at 1 yr, tonic-clonic, myoclonic and focal with head deviation at 2 yr | Tonic-clonic, tonic-atonic, focal and focal with secondary generalization | Tonic-clonic, atonic, focal and infantile spasms | Tonic-clonic, atypical absence, atonic, infantile spasms and focal dyscognitive |
EEG findings | Diffuse polyspikes and waves with intermittent multifocal spikes at 1yr 6mo | Generalized discharges of high amplitude spikes-waves and polyspikes at 2 yr 11 mo | Mild diffuse slowing and abundant bihemispheric multifocal epileptiform discharges | Hypsarrhythmia at 8 mo, diffuse polyspikes, diffuse polyspikes-waves, right temporal spikes and waves, left occipital spikes and diffuse polyspike bursts at 5 yr | Unspecified |
Response to therapy | Refractory | Refractory | Refractory | Refractory | Unknown |
Hypotonia | + | − | + | + | N.D. |
Involuntary movement | Choreic and myoclonic movement of the upper limbs | − | N.D. | Stereotyped handwringing movements | N.D. |
Intellectual disability | Severe (no words) | Severe (no words) | + | + | Unspecified |
Motor development | Unable to sit by 4 yr | Walking at 2 yr 6 mo | Delayed | Walking at 2 yr 6 mo | Unspecified |
MRI findings | Normal at 9 mo, progressive brain atrophy at 1 yr 6 mo and 2 yr 2 mo | Normal at 2 yr 3 mo | Subtle volume loss in the left hippocampus | Normal at 9 mo | Normal |
Other notes | − | Tantrum bursts, macrocephaly | Intermittent agitation, strabismus, migraine | Strabismus, tremulousness, nonverbal, in-turning of feet | Cerebral palsy |
