HTT (Huntingtin) is a disease gene linked to Huntington's disease, a neurodegenerative disorder characterized by loss of striatal neurons. This is thought to be caused by an expanded, unstable trinucleotide repeat in the HTT gene, which translates as a polyglutamine repeat in the protein product. A fairly broad range in the number of trinucleotide repeats has been identified in normal controls, and repeat numbers in excess of 40 have been described as pathological. The huntingtin gene is widely expressed and is required for normal development. In adults, it functions in vesicle trafficking, and is thought to participate in cytoskeletal anchoring and mitochondrial transport. In normal tissue, HTT has highest cytoplasmic and nuclear positivity in the brain, and is also found in most other tissues throughout the body. References: The UniProt Consortium. Nucleic Acids Res. 47: D506-515 (2019); Nucleic Acids Res. 2016 Jan 4;44(D1):D733-45, PMID:26553804; Journal of Cell Science. 115 (Pt 5): 941–8, PMID: 11870213;