Table 1.
Clinical features of patients in the study.
| Patient | Patient 1 | Patient 2 | Patient 3 |
|---|---|---|---|
| Variant | c.1300G>C (p.Val434Leu) | c.1294G>A (p.Val432Met) | c.1290G>A (p.Met430Ile) |
| Inheritance | De novo | De novo | De novo |
| Age at symptom onset (current age) | 2 months (18 months) | 3 months (3 years) | 2 years (5 years) |
| First sign/symptom | Nystagmus | Hypotonia | Gross motor delay (walked at age 20 mo) |
| Developmental delay | Moderate–severe | Mild–moderate | Mild |
| Central hypotonia | Yes | Yes | Yes |
| Seizures/epilepsy | No | No | No |
| Ataxia | No | Mild gait ataxia | No |
| Myoclonus | None | None | None |
| Progression | None | None | None |
| Other | Nystagmus | None | None |
| EEG | C3/Cz sharps during sleep | Not performed | Not performed |
| MRI brain | Normal | Normal | Not performed |