ELOVL4 and Intellectual disability: A potential problem of such inhibition is that too low a level can also cause severe neurological abnormalities, as well as other physiological dysfunction, as clearly demonstrated by mutations in ELOVL4. Heterozygous ELOVL4 mutations cause autosomal dominant spinocerebellar ataxia32 or macular dystrophy33, whereas homozygous ELOVL4 mutations cause intellectual disability, spastic quadriplegia and ichthyosis34.