Epilepsy is seen in 91 % of affected individuals with a mean age at seizure onset of 13 months (median age 8 months, range 0–156 months) with 30% of affected individuals achieving seizure control. Individuals with the variant p.(Arg294His) associated with hereditary spastic paraplegia and ataxia are less likely to develop seizures. Febrile seizures were described in 28% of individuals.
Developmental delay/Intellectual disability (DD/ID) of varying degree is seen in 82 % of affected individuals. Some individuals may have normal intellect.
Movement Disorders are seen in 95 % of affected individuals with ataxia being most prevalent (seen in 64 %), followed by tremor (23 %) and spasticity (16 %).
Cranial magnetic resonance imaging is abnormal in 40 %, with cerebellar atrophy being most commonly reported.
KCNA2