DYRK1A and microcephaly: Surprisingly, mice with heterozygous inactivation of Dyrk1a in developing excitatory neurons of the cortex (Dyrk1aEmx1/+) presented decreased cortical thickness and increased cell density due to smaller excitatory neurons only at birth, while adult microcephaly was associated to fewer neurons due to increased apoptosis leading to postnatal cell death [58].