Kennedy disease
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: X-linked spinal-bulbar muscular atrophy; SBMA; KD; bulbospinal muscular atrophy
Overview
Overview
Kennedy’s disease is a neuromuscular disease associated with mutations of the androgen receptor (AR). Because of its endocrine manifestations related to the impairment of the AR, it can be viewed as a variation of the disorders of the androgen insensitivity syndrome (AIS)[1][2][3].
References
- ↑ La Spada A, Wilson EM, Lubahn DB, Harding AE, Fischbeck KH. Androgen receptor gene mutations in X-linked spinal and bulbar muscular atrophy. Nature 1991;352:77-79.
- ↑ Fischbeck KH, Lieberman A, Bailey CK, Abel A, Merry DE. Androgen receptor mutation in Kennedy’s disease. Phil Trans R Soc Lond B 1999;354:1075-1078.
- ↑ Chen CJ, Fischbeck KH: Clinical aspects and the genetic and molecular biology of Kennedy’s disease. In: Wells RD, Ashizawa T (eds.): Genetic Instabilities and Neurological Diseases, Second Edition. San Diego, Academic Press/Elsevier, 2006.
Historical Perspective
Overview
Historical Perspective
It is named after WR Kennedy, a neurologist who was among the first to describe this disease [1].This disorder was described by Kennedy in 1968. In 1991 it was recognized that the AR is involved in the disease process. The disease is probably more common than originally thought. A study in Scandinavia suggested a prevalence of 1.3/8,500 making KD the most common form of motor neuron disease in the specific area studied; nobody had been diagnosed before 1995. It has been suggested that some men with KD may be misdiagnosed to have amyotrophic lateral sclerosis (ALS, also Lou Gehrig’s disease).
References
- ↑ Kennedy WR, Alter M, Sung JH. Progressive proximal spinal and bulbar muscular atrophy of late onset: a sex-linked recessive trait. Neurology 1968;18:671-680. PMID 4233749.
Classification
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References
Pathophysiology
Overview
Pathophysiology
Genetics
The gene for the androgen receptor is located on the X chromosome (Xq11-q12), making it a sex-linked disease, thus KD generally affects males. Females are rarely affected; female carriers tend to have a relatively mild expression of the disease if they show symptoms at all.
- Homozygous females
Homozygous females, both of whose X chromosomes have a mutation leading to CAG expansion of the AR gene, have been reported to show only mild symptoms of muscle cramps and twitching. No endocrinopathy has been described.
Pathology
Kennedy disease, reported in 1991, involves multiplied CAG repeats in the first exon (trinucleotide repeats). Inheritance is X-linked recessive with anticipation. Such a CAG repeat encodes a polyglutamine tract in a part of the androgen receptor outside of the binding sites. The more CAG repeats are present, the more severe the disease. The mechanism by which this type of mutaion causes neuromuscular disease is not completely understood, specifically as complete AIS does not affect neuromuscular activity. KD may share mechanistic features with other neurodegenerative disorders that are caused by polyglutamine expansion, such as Huntington’s disease. There is currently no treatment or cure for Kennedy’s Disease.
References
Causes
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References
Differentiating Kennedy Disease from other Diseases
Epidemiology and Demographics
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Risk Factors
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Natural History, Complications and Prognosis
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Diagnosis
Diagnosis
History and Symptoms | Physical Examination | Laboratory Findings | CT | MRI | Ultrasound | Other Imaging Findings | Other Diagnostic Studies
Treatment
Treatment
Medical Therapy | Surgery | Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therpies
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