Spinal and bulbar muscular atrophy

This article is about a type of spinal muscular atrophy linked to a genetic defect in the AR gene. For a list of other conditions with similar names, see Spinal muscular atrophies.
Spinal and bulbar muscular atrophy
Other namesKennedy's disease (KD), spinobulbar muscular atrophy, bulbo-spinal atrophy, X-linked bulbospinal neuropathy (XBSN), X-linked spinal muscular atrophy type 1 (SMAX1), and many other names[1]
This disorder is inherited via X-linked recessive manner
SpecialtyNeurology Edit this on Wikidata
SymptomsWeakness of limb and bulbar muscles, tremor, fasciculations, muscle cramps, dysarthria and dysphagia
CausesMutation in the AR gene
Diagnostic methodNumber of CAG repeats in the AR gene
TreatmentSupportive Care

Spinal and bulbar muscular atrophy (SBMA), popularly known as Kennedy's disease, is a rare, adult-onset, X-linked recessive lower motor neuron disease caused by trinucleotide CAG repeat expansions in exon 1 of the androgen receptor (AR) gene, which results in both loss of AR function and toxic gain of function.[2][3]

In men, the disease slowly progresses over decades with bulbar and lower motor neuron loss, muscle denervation, and direct skeletal muscle involvement.[4][5]  The disease causes progressive muscle loss with weakness, fasciculations, and cramps.  Weakness of the bulbar muscles follows causing difficulties in speech (dysarthria) and swallowing (dysphagia). Female carriers do not show symptoms.  Although there is no cure, supportive intervention can improve mobility and reduce complications. The prevalence of SBMA has been estimated at 2.6:100,000 males.[6]

There is no known cure for SBMA.[7][8][9] Supportive care is focused on preventing disease complications and maintaining independence. 

  1. ^ Arvin, Shelley (2013-04-01). "Analysis of inconsistencies in terminology of spinal and bulbar muscular atrophy and its effect on retrieval of research". Journal of the Medical Library Association. 101 (2): 147–150. doi:10.3163/1536-5050.101.2.010. ISSN 1536-5050. PMC 3634378. PMID 23646030.
  2. ^ Chen CJ, Fischbeck KH (2006). "Ch. 13: Clinical aspects and the genetic and molecular biology of Kennedy's disease". In Tetsuo Ashizawa, Wells, Robert V. (eds.). Genetic Instabilities and Neurological Diseases (2nd ed.). Boston: Academic Press. pp. 211–222. ISBN 978-0-12-369462-1.
  3. ^ Cite error: The named reference :4 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference pmid4233749 was invoked but never defined (see the help page).
  5. ^ A, La Spada (1993–2020). "Spinal and Bulbar Muscular Atrophy". GeneReviews [Internet]. PMID 20301508.
  6. ^ Laskaratos, Achilleas; Breza, Marianthi; Karadima, Georgia; Koutsis, Georgios (2020-06-22). "Wide range of reduced penetrance alleles in spinal and bulbar muscular atrophy: a model-based approach". Journal of Medical Genetics. 58 (6): jmedgenet–2020–106963. doi:10.1136/jmedgenet-2020-106963. ISSN 0022-2593. PMID 32571900. S2CID 219991108.
  7. ^ Cite error: The named reference pmid16389310 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference :12 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference :052 was invoked but never defined (see the help page).