ATP13A2 and Intellectual disability: Namely, Kufor-Rakeb syndrome is predominantly characterized by dementia and extrapyramidal parkinsonian syndrome; SPG78 by cognitive, pyramidal and cerebellar defects; CLN12 by spinocerebellar ataxia and cognitive decline; and the ALS-phenotype described here by intellectual disability, prominent upper and lower motor neuron degeneration, and cerebellar and cerebral atrophy.