And in low-grade choroid plexus papillomas, AQP1 expression had no significant polarity, no clear expression pattern, and each patient had a significant difference, and AQP1 expression on the normal choroid plexus had a significant polarity completely opposite, but this study was unattended (Longatti et al., 2006). The gene discussed is AQP1; the disease is choroid plexus papilloma.