We then assessed whether these cells can respond to Ihh using quantitative PCR (qPCR) to determine the expression level of Hh target genes Ptch1 and Gli1. Compared to WT, there is a significant decrease in Ptch1 expression in KC ductal cysts (Fig. 3B; P<0.002, n=6), indicating that the presence of fewer cilia in KC ductal cysts reduces the response of these cells to Hh signals. The gene discussed is PTCH1; the disease is keratoconus.