The hallmark in patients with a severe form of SPTAN1 encephalopathy (OMIM #613477, DEE5) is infantile onset of developmental and epileptic encephalopathy together with progressive atrophy of the cerebellum and brainstem. These patients showed spastic quadriplegia with severe developmental delay. Infantile spasms are the most prominent seizure type. Brain MRI revealed progressive brain, brainstem, and cerebellar atrophy with cerebral hypomyelination. The high prevalence of early childhood death was reported in SPTAN1 encephalopathy. The patients with milder form manifest complex phenotypes with less severe DD/ID and with or without different types of child-onset epilepsy without any sign of progression. The third group consists of patients with pure or complex HSP and ataxia. Rarely, families with hereditary motor neuropathy were reported.
SPTAN1