A complete loss of the NPHP1 signal was also detected in the scenario of a pathogenic NPHP4 genotype as presented by individual ON-201 II1 carrying a homozygous NPHP4 frameshift mutation (c.3272del; p.Val1091fs) and clinically displaying an isolated NPH phenotype (Fig. 2d). This evidence concerns the gene NPHP4 and normal pressure hydrocephalus.