Growth retardation and lethal hydrocephalus in α-adducin–null mice. (A-C) α-Adducin–null mice are smaller at birth and throughout life compared with their normal littermates. Blue in panel C indicates X plus or minus SE. (D) Approximately 50% of α-adducin–null mice develop hydrocephalus with extreme dilation of the lateral and third ventricles. The fourth ventricle is also enlarged and the cerebral aqueduct is open (not shown), indicating communicating hydrocephalus. Significant thinning of the cortex is apparent as hydrocephalus worsens. Hydrocephalus was not observed in wild-type or heterozygous mice. C indicates cerebral cortex; CP, choroid plexus; HC, hippocampus; TA, thalamus; HTA, hypothalamus; LV, lateral ventricle; V3, third ventricle; +/+, wild-type; and −/−, homozygous null.