The phenotypes in these 4 cases with a mosaic state were milder than expected for a germinal mutation: two males with DCX mutations (MDC1034 and MDC1092) and a woman with a PAFAH1B1 mutation (MDC1070), presenting with HBS instead of lissencephaly; and a woman with a somatic DCX mutation with a very thin predominantly anterior band of less than 4 mm without intellectual disability. This evidence concerns the gene DCX and Lissencephaly.