TUBG1 and polymicrogyria: The observation that TUBG1 causes undermigration leading to pachygyria or agyria can possibly be explained by a negative impact on cell morphology in patients carrying a TUBG1 variant, while variants in other tubulin genes are more often associated with dysgyria or overmigration presenting as polymicrogyria which suggests defective radial glial guidance of immature neurons [8].