AQP4 and pseudotumor cerebri: Anti-aquaporin 4 antibodies have not been identified in IIH,17 and there is no evidence of upregulation of the aquaporin 4 gene.18 Aquaporin 1 is another candidate as these channels are predominantly in the choroid plexus, can be upregulated by retinoids and glucocorticoids, and are affected by medications used to treat IIH.