Definition:

Cystic leukoencephalopathy without megalencephaly is an autosomal recessive infantile-onset neurological disorder. The affected individuals are asymptomatic at birth and show a static encephalopathy with normo- or microcephaly and psychomotor impairment within the first year of life. Brain magnetic resonance imaging (MRI) shows bilateral anterior temporal lobe cystic lesions and enlarged inferior horns combined with multifocal white matter alterations. Loss-of-function mutations in the gene encoding the RNASET2 glycoprotein lead to this disorder.