Focal cortical dysplasias (FCDs) are localized MCDs, formerly believed to mostly result from a toxic insult to the developing brain, but recently also associated with DEPDC5 mutations [25] and somatic mutations in MTOR, PIK3CA, AKT3, PTEN, TSC1 and TSC2 [26]. The gene discussed is PTEN; the disease is Schmid metaphyseal chondrodysplasia.