Homozygous loss-of-function mutations in RELN are associated with an autosomal recessive form of lissencephaly; Lissencephaly 2 (Norman-Roberts type) [MIM #257320]. DECIPHER clinical database entry of a de novo ~120 kb intragenic RELN deletion in a patient with lissencephaly/pachygyria, MR/DD, and a wide forehead and no other copy number alterations. PMID21841781: In a study comparing a large cohort of children with ID and/or DD to unaffected adult controls, there is one intragenic deletion in the cases. No phenotypic information was provided.