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Disease Profile

Kennedy disease

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Spinal and bulbar muscular atrophy; X-linked spinal and bulbar muscular atrophy; Bulbospinal muscular atrophy;


Congenital and Genetic Diseases; Male Reproductive Diseases; Nervous System Diseases


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]


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.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Decreased fertility
Abnormal fertility
Difficulty articulating speech
Inability to produce voice sounds
Erectile dysfunction
Abnormal erection
Erectile abnormalities

[ more ]

Gait disturbance
Abnormal gait
Abnormal walk
Impaired gait

[ more ]

Enlarged male breast
Decreased reflex response
Decreased reflexes

[ more ]

Muscular hypotonia
Low or weak muscle tone
Skeletal muscle atrophy
Muscle degeneration
Muscle wasting

[ more ]

5%-29% of people have these symptoms
Abnormal circulating lipid concentration
Testicular atrophy
Testicular degeneration
Type II diabetes mellitus
Noninsulin-dependent diabetes
Type 2 diabetes
Type II diabetes

[ more ]

Percent of people who have these symptoms is not available through HPO
Abnormality of the mouth
Abnormal mouth
Adult onset
Symptoms begin in adulthood
Bulbar palsy
Calf muscle hypertrophy
Increased size of calf muscles
Poor swallowing
Swallowing difficulties
Swallowing difficulty

[ more ]

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 ]

Muscle twitch
Limb muscle weakness
Limb weakness
Muscle spasm
Peripheral neuropathy
Sensory neuropathy
Damage to nerves that sense feeling
Slow progression
Signs and symptoms worsen slowly with time
X-linked recessive inheritance


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]


    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

      Organizations Providing General Support

        Learn more

        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.


            1. Josef Finsterer. Kennedy disease. Orphanet. July 2011; https://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; https://www.ncbi.nlm.nih.gov/books/NBK1333/.
            3. Spinal and bulbar muscular atrophy. Genetics Home Reference. May 2006; https://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; https://emedicine.medscape.com/article/1172604-overview.

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