National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Kennedy disease


Other Names:
Spinal and bulbar muscular atrophy; X-linked spinal and bulbar muscular atrophy; Bulbospinal muscular atrophy; Spinal and bulbar muscular atrophy; X-linked spinal and bulbar muscular atrophy; Bulbospinal muscular atrophy; X-linked bulbospinal amyotrophy; Spinobulbar muscular atrophy; SBMA See More
Categories:
Kennedy disease is a gradually progressive, neuromuscular disorder characterized by wasting of the proximal muscles (those closer to the trunk) and bulbar muscles (those of the face and throat).The condition mainly affects males, with onset between the ages of 30 and 60.[1] Early symptoms may include tremor, muscle cramps, and muscle twitching. This is followed by progressive muscle weakness and wasting, which may manifest in a variety of ways.[1][2] Affected people may also have gynecomastia, testicular atrophy (reduction in size or function of the testes), and reduced fertility as a result of mild androgen insensitivity.[2] Kennedy disease is caused by a mutation in the androgen receptor (AR) gene and is inherited in an X-linked recessive manner. Treatment may include physiotherapy and rehabilitation; medications to alleviate tremor and muscle cramps; and hormone therapy or surgical treatment for gynecomastia.[1][2]
Last updated: 9/21/2015

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
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HPO ID
80%-99% of people have these symptoms
Decreased fertility
Abnormal fertility
0000144
Dysarthria
Difficulty articulating speech
0001260
Dysphonia
Inability to produce voice sounds
0001618
Erectile dysfunction
Abnormal erection
Erectile abnormalities
[ more ] 		0100639
Gait disturbance
Abnormal gait
Abnormal walk
Impaired gait
[ more ] 		0001288
Gynecomastia
Enlarged male breast
0000771
Hyporeflexia
Decreased reflex response
Decreased reflexes
[ more ] 		0001265
Muscular hypotonia
Low or weak muscle tone
0001252
Skeletal muscle atrophy
Muscle degeneration
Muscle wasting
[ more ] 		0003202
5%-29% of people have these symptoms
Abnormal circulating lipid concentration 0003119
Testicular atrophy
Testicular degeneration
0000029
Type II diabetes mellitus
Noninsulin-dependent diabetes
Type 2 diabetes
Type II diabetes
[ more ] 		0005978
Percent of people who have these symptoms is not available through HPO
Abnormality of the mouth
Abnormal mouth
0000153
Adult onset
Symptoms begin in adulthood
0003581
Bulbar palsy 0001283
Calf muscle hypertrophy
Increased size of calf muscles
0008981
Dysphagia
Poor swallowing
Swallowing difficulties
Swallowing difficulty
[ more ] 		0002015
Elevated serum creatine kinase
Elevated blood creatine phosphokinase
Elevated circulating creatine phosphokinase
Elevated creatine kinase
Elevated serum CPK
Elevated serum creatine phosphokinase
High serum creatine kinase
Increased CPK
Increased creatine kinase
Increased creatine phosphokinase
Increased serum CK
Increased serum creatine kinase
Increased serum creatine phosphokinase
[ more ] 		0003236
Fasciculations
Muscle twitch
0002380
Limb muscle weakness
Limb weakness
0003690
Muscle spasm 0003394
Peripheral neuropathy 0009830
Sensory neuropathy
Damage to nerves that sense feeling
0000763
Slow progression
Signs and symptoms worsen slowly with time
0003677
Tremor 0001337
X-linked recessive inheritance 0001419
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Last updated: 7/1/2020
Kennedy disease is inherited in an X-linked recessive manner. A condition is X-linked if the mutated responsible gene 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 enough to cause the condition. In females, a mutation usually must be present in both copies of the gene (one on each X chromosome) to cause the condition.[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% chance to pass the mutated gene on to each daughter (i.e. there is a 50% chance each daughter will also be a carrier) and a 50% chance to pass the mutated gene on to each son (i.e. there is a 50% chance that each son will be affected).
Last updated: 9/21/2015

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
There is currently no cure for Kennedy disease. Treatment aims to relieve symptoms, maintain maximal function, and improve quality of life. Physical therapy and rehabilitation, including the use of braces and walkers, are the best chance for remaining ambulatory as the disease progresses. Some people with Kennedy disease have breast reduction surgery for gynecomastia.[2] The use of anti-androgens have been shown to improve some aspects of the disease is some people; the androgen-dependent nature of the disease is the rationale for the use of anti-androgens in treating Kennedy disease.[4]

Complications resulting from bulbar weakness, such as asphyxiation and aspiration pneumonia, can be life threatening. People with bulbar weakness should be counseled on the importance of cutting their food into small pieces for eating, and avoiding items that may be difficult to chew and then swallow.[2]

The severity and progression of Kennedy disease should be monitored. Because it is slowly progressive, it is important to periodically assess strength and tolerance to exertion. This allows for proactive management to minimize the risk for falls, optimize mobility, and provide appropriate assistive devices.[4]
Last updated: 9/21/2015

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
Differential diagnoses include hereditary spastic paraplegia, spinocerebellar ataxia (see these terms), other motor neuron diseases, myopathies, neuropathies, lead or aluminum poisoning, and cervical spondylosis.
Visit the Orphanet disease page for more information.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Kennedy disease. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • MeSH® (Medical Subject Headings) is a terminology tool used by the National Library of Medicine. Click on the link to view information on this topic.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Kennedy disease. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • I want to know more about this disease, especially the newest treatment of this disease. How can I get more useful information? See answer

  • I have Kennedy disease. Lately, I've had trouble coughing up phlegm. I've also been hoarse and at times have a weak and raspy voice. An ENT told me two years ago that I have lost some elasticity in my larynx. Does Kennedy disease cause these types of problems? See answer

  • My wife is showing many symptoms of this disease and is a confirmed carrier. Is it possible that she has it? See answer


  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. July 3, 2014; http://www.ncbi.nlm.nih.gov/books/NBK1333/.
  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.
  4. Paul E Barkhaus. Kennedy disease. Medscape Reference. March 11, 2014; http://emedicine.medscape.com/article/1172604-overview.