Kennedy disease

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.

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. 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).

Females who are carriers of an abnormal CAG expansion in the androgen receptor (AR) gene are usually unaffected, but some may have mild signs and symptoms including muscle cramps or occasional tremors. No reported female carriers have had significant motor neuron disease. Females who are symptomatic may have an abnormal electromyogram or abnormal findings on muscle biopsy.

Yes. Therapies for Kennedy disease under investigation have included:

• High-dose testosterone - At least one clinical trial of high-dose oral testosterone has been undertaken, and no significant benefit was seen for the androgen treatment group. Based on research in Drosophila and mouse models, many researchers believe that androgen treatment can be harmful.
• Anti-androgen therapy - There is no consensus or clear evidence as to whether anti-androgen therapy is an effective treatment for the neurologic complications of Kennedy disease. However, anti-androgen therapy shows promise based on studies in Drosophila and mouse models as well as knowledge of the molecular basis of Kennedy disease. More detailed information about anti-androgen therapy for Kennedy disease is available on the GeneReviews Web site under Therapies Under Investigation.
• Creatine supplementation - Recent studies of amyotrophic lateral sclerosis (ALS) suggest that creatine supplementation may temporarily enhance muscle strength and exercise performance, prompting speculation that it may offer a similar benefit to people with Kennedy disease; however, this remains to be tested.
• Experimental therapies in animal models - Some interventions have been shown to be beneficial in mouse models; these studies have suggested that muscle-directed therapies hold great promise as treatments for Kennedy disease.

The U.S. National Institutes of Health, through the National Library of Medicine, developed ClinicalTrials.gov to provide patients, family members, and members of the public with current information on clinical research studies. There are a number of ongoing and completed trials relating to treatment options for Kennedy disease.

You can view the list of clinical trials for Kennedy disease here. Use each study’s contact information to learn more. This site can be checked often for updates.

You can also find relevant articles about the treatment of Kennedy disease through PubMed, a searchable database of biomedical journal articles. Although not all of the articles are available for free online, most articles listed in PubMed have a summary available.

A sample search for information about the treatment of Kennedy disease is available here.

To obtain a full article, contact a medical/university library or your local library for interlibrary loan. You can also order articles online through the publisher’s Web site. The National Library of Medicine (NLM) Web site has a page for locating libraries in your area that can provide direct access to these journals (print or online). The Web page also describes how you can get these articles through interlibrary loan and Loansome Doc (an NLM document- ordering service). You can access this page at the following link: http://nnlm.gov/members/. You can also contact the NLM toll-free at 888-346-3656 to locate libraries in your area.

While Kennedy disease does not impair the lungs themselves, the disease can weaken the muscles involved in breathing and coughing. As your respiratory muscles become weaker, you may find it more difficult to bring up phelgm and maintain clear airways.

The Muscular Dystrophy Canada has developed a guide on respiratory care for people with neuromuscular disorders that gives further detailed information on this topic. You can view a PDF copy of this guide at the following link:
http://www.muscle.ca/fileadmin/National/Muscular_Dystrophy/Respiratory_Care/RC13guide- E_finalWEB.pdf

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. 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. 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. 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.

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. 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.

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.

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.