Your browser does not support javascript:   Search for gard hereSearch for news-and-events here.

Diseases

Genetic and Rare Diseases Information Center (GARD)

Print friendly version

Kennedy disease


Other Names for this Disease

  • Bulbospinal muscular atrophy
  • SBMA
  • Spinal and bulbar muscular atrophy
  • Spinobulbar muscular atrophy
  • X-linked bulbospinal amyotrophy
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Overview

What is Kennedy disease?

How is Kennedy disease inherited?

What is Kennedy disease?

Kennedy disease is a gradually progressive neuromuscular disorder chiefly characterized by wasting of the proximal muscles (those closer to the trunk) and bulbar muscles (those of the face and throat).[1][2] The condition mainly affects males, with onset between the ages of 30 and 60.[1][2] Early signs and symptoms may include tremor, muscle cramps and muscle twitching, followed by progressive muscle weakness and wasting which may manifest in a variety of ways.[1][2] Affected individuals may also have gynecomastia, testicular atrophy (reduction in size or function), and reduced fertility.[2] It is caused by a mutation in the androgen receptor (AR) gene, in which a DNA segment known as a CAG triplet repeat is abnormally expanded.[3] It is inherited in an X-linked recessive manner. Treatment may include physiotherapy and rehabilitation, medications for tremor and muscle cramps, and hormone therapy or surgical treatment of gynecomastia.[1]
Last updated: 9/28/2012

How is Kennedy disease inherited?

Kennedy disease is inherited in an X-linked recessive manner. A condition is considered X-linked if the mutated gene that causes the condition is located on the X chromosome (one of the two sex chromosomes). Males have one X chromosome and one Y chromosome, while females have two X chromosomes. In males, one mutated copy of a disease-causing gene on the X chromosome is sufficient to cause the condition. In females, a mutation typically must be present in both copies of the gene (one on each X chromosome) to cause the disorder to fully manifest.[3]

A characteristic of X-linked inheritance is that affected males cannot pass X-linked traits to their sons because they only pass their Y chromosome to their sons.[3] However, all daughters of an affected male will be carriers of the condition. A female carrier of an X-linked recessive condition has a 50% risk to pass the mutated gene on to each daughter (i.e. there is a 50% risk each daughter will also be a carrier) and a 50% risk to pass the mutated gene on to each son (i.e. there is a 50% risk that each son will be affected).
Last updated: 9/28/2012

References
  1. Josef Finsterer. Kennedy disease. Orphanet. July 2011; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=481. Accessed 9/28/2012.
  2. Albert La Spada. Spinal and Bulbar Muscular Atrophy. GeneReviews. October 13, 2011; http://www.ncbi.nlm.nih.gov/books/NBK1333/. Accessed 9/28/2012.
  3. Spinal and bulbar muscular atrophy. Genetics Home Reference. May 2006; http://ghr.nlm.nih.gov/condition/spinal-and-bulbar-muscular-atrophy. Accessed 9/28/2012.


Other Names for this Disease
  • Bulbospinal muscular atrophy
  • SBMA
  • Spinal and bulbar muscular atrophy
  • Spinobulbar muscular atrophy
  • X-linked bulbospinal amyotrophy
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.