Gender | Female | Male | Male |
Family history | – | – | – |
Age at onset/at death | Birth/24 days | 7 months/3 years 11 months | 4 months/still alive (16 years) |
Neurological signs | Hypotonia | Axial hypotonia | Axial hypotonia |
| Epileptic seizures | Limb spasticity | Limb spasticity |
| | Bulbar signs | Cerebellar tremor |
| | Nystagmus, retinopathy microcephaly | Eye movement incoordination |
| | | Dystonia |
Hypertrophic cardiomyopathy | + | – | – |
Other clinical features | Midfacial hypoplasia | Gastrointestinal dysfunction | Somatic growth below 3rd centile |
Plasma lactate (mM) | Increased | 5.2 | 3.6 |
CSF lactate (mM) | NS | 6.2 | 3.8 |
Brain MRI | NS | Basal nuclei | Basal ganglia (putamina, caudate) |
| | Brainstem tegmentum | Cerebellar white matter |
| | Cerebral peduncles | |
Mutations | 700C→T, C447-3G | 700C→T, 700C→T | 503C→G, 1081T→C |