Early-onset epilepsy-5 with or without developmental delay (EPEO5) is an autosomal recessive neurologic disorder characterized by the onset of various types of seizures late in the first decade or during adolescence. Focal seizures are common. Most affected individuals have developmental delay, variable impaired intellectual development, and/or behavioral and neuropsychiatric abnormalities (Stogmann et al., 2013; Abdulkareem et al., 2023). For a discussion of genetic heterogeneity of EPEO, see 617290.

Autosomal recessive spastic ataxia-10 (SPAX10) is a slowly progressive movement disorder with a variable age at onset (range infancy to adulthood). Affected individuals present with gait abnormalities due to spasticity and hyperreflexia of the lower limbs and/or cerebellar gait and limb ataxia. More variable features may include dysarthria, saccadic eye movements, and mild cognitive impairment. Some patients show cerebellar atrophy on brain imaging. The disorder can be classified as a movement disorder on the ataxia-spasticity spectrum (ASS) (Cordts et al., 2022). For a discussion of genetic heterogeneity of spastic ataxia, see SPAX1 (108600).