In this study, we show that two dominant (MmTMC1/CmTMC1: M412K/M507K and D569N/D658N) and one recessive (D528N/D617N) deafness-causing mutations enable TMC1 to scramble lipids in the presence of physiological cholesterol levels, resulting in constitutive externalization of PS (Figure 7B). Here, TMC1 is linked to deafness.