AQP4 and Hydrocephalus: Therefore, to elucidate the differences in the transcriptome between AQP4-KO-CD1 animals that develop obstructive hydrocephalus with that of AQP4-KO-CD1 siblings from the same litter that did not develop hydrocephalus, we performed a study of differential gene expression in the aqueduct of Sylvius of both type of animals, as well as control or wild-type (WT) mice, using microarray technology from Affymetrix.