CLDN5 and Machado-Joseph disease: On the contrary, levels of a 27 kDa monomer of claudin-5, exhibited a 2-fold increase in MJD transgenic mice when compared to wild-type animals (0.34 ± 0.047 in wild-type, n = 7 vs 0.69 ± 0.087 in MJD, n = 7; unpaired t test, P = 0.005) (Fig. 5f).