Recently disease-causing gain-of-function mutations in the CCND2 gene was identified in patients with megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome-3 (MPPH3; MIM 615938) (Mirzaa et al., 2014). This evidence concerns the gene CCND2 and megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome 3.