MAPT and Huntington disease: We next looked at the 3R- and 4R-tau isoform mRNA levels of expression and, in line with the recent report from Fernández-Nogales et al. (2014), found an increased expression of the 4R-tau isoforms transcripts (Supplementary Fig. 4A) and a consequent altered 4R:3R tau transcript ratio in both the cortex (1.261 ± 0.146) and striatum (1.446 ± 0.264) of Huntington’s disease cases versus controls (cortex = 1.037 ± 0.012 and striatum = 1.033 ± 0.059) (Supplementary Fig. 4B).