Distinguishing features include a more severe presentation with early lethality, lissencephaly, severe microcephaly, overlapping fingers, post-axial polydactyly of the feet, talipes, agenesis of the corpus callosum and unilateral renal agenesis in DREAM-PL, and the unusual synpolydactyly, short fingers and fingernail and toenail dysplasia in MAPKAPK5-related NDD. This evidence concerns the gene MAPKAPK5 and lissencephaly spectrum disorders.