NPC1 expression in NPC variant cell models. (A) Schematic overview of the process of cell model generation and characterization. (B) Expression of NPC1 mRNA is significantly decreased in the NPC1 p.R1077X cell model (n = 3, P = 0.002 by two-tailed t-test) but is unchanged in all other variants assayed. (C, top) Diagram illustrating PCR assay used to analyze splicing. (Middle) PCR amplification results in a shorter amplicon in NPC1 c.3591+2T>C cells compared with the wild type. (Bottom) Sequencing chromatogram from NPC1 c.3591+2T>C cells showing exclusion of exon 23.