SOX10 and Charcot-Marie-Tooth disease type 1A: Furthermore, in the S16 rat Schwann cell line, depletion of Sox10 reduced TMPRSS5 level, indicating that Tmprss5, like many other myelin genes, is regulated by this critical transcription factor required for Schwann cell development.35 While it is not yet clear that increased TMPRSS5 levels in plasma are due to enhanced release from Schwann cells and/or increased synthesis, the Tmprss5 transcript is elevated in a recently published profile of the rat CMT1A model,45 and analysis of the C3 model of CMT1A showed a similar elevation of the Tmprss5 transcript.