At birth, mice homozygous for this targeted allele are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. Cdk5r protein product is not immunodetectable in homozygote whole-brain lysates. Histological analysis of homozygotes reveals severe defects in the patterning of the cerebral cortex and other areas of the brain. The normal lamination pattern of cortical neurons is disrupted; axonal trajectories and dendritic structures are altered. Homozygous mice are more susceptible to mortality from chemically induced-seizures. Sporadic adult lethality is also observed, presumably resulting from spontaneous seizures, a consequence of the disrupted cytoarchitecture observed in the cortex. This mutant mouse strain represents a model that may be useful in studies related to the mechanisms of cortical lamination, epilepsy, Alzheimer's and other neurodegenerative diseases. The Jackson Laboratory 2024, used with permission.