The identification of a sub-haplotype of H1, namely H1c, and a crucial SNP, rs242557, within a downstream repressor domain in the MAPT promoter that defines the H1c haplotype (Pittman et al., 2005), provided evidence that the basis of the association with PSP lies in allelic differences in gene expression (Myers et al., 2007). The gene discussed is MAPT; the disease is supranuclear palsy, progressive, 1.