TBP and juvenile Huntington disease: For example, Reid and colleagues have identified an aggregation-prone splice isoform of TBP, the disease protein in SCA17, which is enriched in its soluble form in Alzheimer disease (AD) and Huntington disease (HD) brains [7]; whether this isoform contributes significantly to SCA17 pathology or is merely a marker of dysregulated splicing in AD and HD is yet to be determined.