Huntington's disease

Huntington's disease
Other namesHuntington's chorea
Several neurons colored yellow and having a large central core with up to two dozen tendrils branching out of them, the core of the neuron in the foreground contains an orange blob about a quarter of its diameter
An edited microscopic image of a medium spiny neuron (yellow) with an inclusion body (orange), which occurs as part of the disease process (image width 360 μm)
SpecialtyNeurology
SymptomsProblems with motor skills including coordination and gait, mood, and mental abilities[1][2]
ComplicationsPneumonia, heart disease, physical injury from falls, suicide[3]
Usual onset30–50 years old[4]
DurationLong term[4]
CausesGenetic (inherited or new mutation)[4]
Diagnostic methodGenetic testing[5]
Differential diagnosisSydenham's chorea, benign hereditary chorea, lupus, paraneoplastic syndrome, Wilson's disease[6]
TreatmentSupportive care[2]
MedicationTetrabenazine[3]
Prognosis15–20 years from onset of symptoms[4]
Frequency4–15 in 100,000 (European descent)[1]
Named afterGeorge Huntington

Huntington's disease (HD), also known as Huntington's chorea, is an incurable neurodegenerative disease[7] that is mostly inherited.[8] The earliest symptoms are often subtle problems with mood or mental/psychiatric abilities.[9][1] A general lack of coordination and an unsteady gait often follow.[2] It is also a basal ganglia disease causing a hyperkinetic movement disorder known as chorea.[10][11] As the disease advances, uncoordinated, involuntary body movements of chorea become more apparent.[1] Physical abilities gradually worsen until coordinated movement becomes difficult and the person is unable to talk.[1][2] Mental abilities generally decline into dementia, depression, apathy, and impulsivity at times.[9][12][3] The specific symptoms vary somewhat between people.[1] Symptoms usually begin between 30 and 50 years of age, and can start at any age but are usually seen around the age of 40.[12][9][3][4] The disease may develop earlier in each successive generation.[1] About eight percent of cases start before the age of 20 years, and are known as juvenile HD, which typically present with the slow movement symptoms of Parkinson's disease rather than those of chorea.[3]

HD is typically inherited from an affected parent, who carries a mutation in the huntingtin gene (HTT).[4] However, up to 10% of cases are due to a new mutation.[1] The huntingtin gene provides the genetic information for huntingtin protein (Htt).[1] Expansion of CAG repeats of cytosine-adenine-guanine (known as a trinucleotide repeat expansion) in the gene coding for the huntingtin protein results in an abnormal mutant protein (mHtt), which gradually damages brain cells through a number of possible mechanisms.[8][13] The mutant protein is dominant, so having one parent who is a carrier of the trait is sufficient to trigger the disease in their children. Diagnosis is by genetic testing, which can be carried out at any time, regardless of whether or not symptoms are present.[5] This fact raises several ethical debates: the age at which an individual is considered mature enough to choose testing; whether parents have the right to have their children tested; and managing confidentiality and disclosure of test results.[2]

No cure for HD is known, and full-time care is required in the later stages.[2] Treatments can relieve some symptoms and in some, improve quality of life.[3] The best evidence for treatment of the movement problems is with tetrabenazine.[3] HD affects about 4 to 15 in 100,000 people of European descent.[1][3] It is rare among the Finnish and Japanese, while the occurrence rate in Africa is unknown.[3] The disease affects males and females equally.[3] Complications such as pneumonia, heart disease, and physical injury from falls reduce life expectancy; although fatal aspiration pneumonia is commonly cited as the ultimate cause of death for those with the condition.[14][12][3] Suicide is the cause of death in about 9% of cases.[3] Death typically occurs 15–20 years from when the disease was first detected.[4]

The earliest known description of the disease was in 1841 by American physician Charles Oscar Waters.[15] The condition was described in further detail in 1872 by American physician George Huntington.[15] The genetic basis was discovered in 1993 by an international collaborative effort led by the Hereditary Disease Foundation.[16][17] Research and support organizations began forming in the late 1960s to increase public awareness, provide support for individuals and their families and promote research.[17][18] Research directions include determining the exact mechanism of the disease, improving animal models to aid with research, testing of medications and their delivery to treat symptoms or slow the progression of the disease, and studying procedures such as stem-cell therapy with the goal of replacing damaged or lost neurons.[16]

  1. ^ a b c d e f g h i j Dayalu P, Albin RL (February 2015). "Huntington disease: pathogenesis and treatment". Neurologic Clinics. 33 (1): 101–114. doi:10.1016/j.ncl.2014.09.003. PMID 25432725.
  2. ^ a b c d e f Caron NS, Wright GE, Hayden MR (2020). Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJ, Stephens K, Amemiya A (eds.). "Huntington Disease". GeneReviews. PMID 20301482.
  3. ^ a b c d e f g h i j k l Frank S (January 2014). "Treatment of Huntington's disease". Neurotherapeutics. 11 (1): 153–160. doi:10.1007/s13311-013-0244-z. PMC 3899480. PMID 24366610.
  4. ^ a b c d e f g "Huntington's Disease Information Page". National Institute of Neurological Disorders and Stroke. Archived from the original on 13 December 2020. Retrieved 14 December 2020.
  5. ^ a b Durr A, Gargiulo M, Feingold J (November 2012). "The presymptomatic phase of Huntington disease". Revue Neurologique. 168 (11): 806–808. doi:10.1016/j.neurol.2012.07.003. PMID 22902173.
  6. ^ Ferri FF (2010). Ferri's differential diagnosis: a practical guide to the differential diagnosis of symptoms, signs, and clinical disorders (2nd ed.). Philadelphia, PA: Elsevier/Mosby. p. Chapter H. ISBN 978-0-323-07699-9.
  7. ^ "Huntington's disease - Treatment and support". National Health Service UK. 23 October 2017. Archived from the original on 6 May 2023. Retrieved 6 May 2023.
  8. ^ a b Illarioshkin SN, Klyushnikov SA, Vigont VA, Seliverstov YA, Kaznacheyeva EV (September 2018). "Molecular Pathogenesis in Huntington's Disease". Biochemistry. Biokhimiia. 83 (9): 1030–1039. doi:10.1134/S0006297918090043. PMID 30472941. S2CID 26471825. Archived from the original on 13 November 2020. Retrieved 8 November 2020 – via protein.bio.msu.ru.
  9. ^ a b c Sudhakar V, Richardson RM (January 2019). "Gene Therapy for Neurodegenerative Diseases". Neurotherapeutics. 16 (1): 166–175. doi:10.1007/s13311-018-00694-0. PMC 6361055. PMID 30542906.
  10. ^ Kumar, Abbas A, Aster J (2018). Robbins basic pathology (Tenth ed.). Philadelphia, Pennsylvania: Elsevier. p. 879. ISBN 978-0-323-35317-5.
  11. ^ Purves D (2012). Neuroscience (5th ed.). Sunderland, Mass.: Sinauer Associates. p. 415. ISBN 978-0-87893-695-3.
  12. ^ a b c Saudou F, Humbert S (March 2016). "The Biology of Huntingtin". Neuron. 89 (5): 910–926. doi:10.1016/j.neuron.2016.02.003. PMID 26938440. S2CID 8272667.
  13. ^ Cite error: The named reference hdprimer was invoked but never defined (see the help page).
  14. ^ "Aspiration Pneumonia: What It Is, Causes, Diagnosis, Treatment". Cleveland Clinic. Archived from the original on 12 June 2023. Retrieved 12 June 2023.
  15. ^ a b Vale TC, Cardoso F (2015). "Chorea: A Journey through History". Tremor and Other Hyperkinetic Movements. 5. doi:10.7916/D8WM1C98 (inactive 1 November 2024). PMC 4454991. PMID 26056609.{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)
  16. ^ a b "About Huntington's Disease". Genome.gov. Archived from the original on 9 January 2021. Retrieved 13 January 2021.
  17. ^ a b "History of the HDF". Hereditary Disease Foundation. Archived from the original on 19 November 2015. Retrieved 18 November 2015.
  18. ^ "History and Genetics of Huntington's Disease | Huntington's Disease Society of America". March 2019. Archived from the original on 1 December 2020. Retrieved 14 December 2020.