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NCBI Description of 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 huntingtin 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 locus is large, spanning 180 kb and consisting of 67 exons. The huntingtin gene is widely expressed and is required for normal development. It is expressed as 2 alternatively polyadenylated forms displaying different relative abundance in various fetal and adult tissues. The larger transcript is approximately 13.7 kb and is expressed predominantly in adult and fetal brain whereas the smaller transcript of approximately 10.3 kb is more widely expressed. The genetic defect leading to Huntington's disease may not necessarily eliminate transcription, but may confer a new property on the mRNA or alter the function of the protein. One candidate is the huntingtin-associated protein-1, highly expressed in brain, which has increased affinity for huntingtin protein with expanded polyglutamine repeats. This gene contains an upstream open reading frame in the 5' UTR that inhibits expression of the huntingtin gene product through translational repression. Sequence Note: This RefSeq was created from transcript sequence data and has been edited to agree with the reference genome except in the CAG repeat region. The reference genome has a repeat region encoding 21 glutamines while the RefSeq has a repeat region (nt 197-265) encoding 23. Neither repeat region is associated with Huntington's Disease.

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Figure notes

• "Mouse over" a mutation to see details.
• Missense green saturation indicates evolutionary conservation of the mutated positions.
• Red hashes in protein strip are splice sites.
• Blue-white-red bars are log2 copy ratio distributions (–1 to +1) from Zack et al. (2013).


HTT is highly significantly mutated in
HTT is significantly mutated in
HTT is near significance in

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Data details

Mutation list for HTT