NPHP1 and normal pressure hydrocephalus: To date, > 25 genes have been linked to NPH (NPHPs), which encode proteins that are playing important roles in PC-mediated signaling functions and/or ciliogenesis.1, 2, 3 The most frequent one is NPHP1 accounting for nearly 25% of NPH cases, mostly harboring a homozygous deletion of the gene.