Kennedy Disease Health Article

Demographics

Because of the X-linked inheritance pattern of Kennedy disease, only males are affected by this disorder. Females may be carriers of the disease if they possess an abnormal gene on one of her X chromosomes. Due to the rare nature of this disease, and the fact that it may frequently be misdiagnosed as another form of neuromuscular disease, no particular race or ethnicity appears to be at greater risk than another.

Kennedy disease is primarily an adult disease, with an onset between the third and fifth decade of life. Once symptoms present, the disease is slowly progressive. In addition to neuronal cell loss, breast enlargement (gynecomatia), reduced fertility and testicular atrophy have also been reported in affected males.

Treatment and management

To date, there is not treatment for SBMA. However, there are possible mechanisms through which treatment could be developed. Gene therapy could be used for SBMA to replace the abnormal gene associated with SBMA with a copy carrying fewer CAG repeats. Currently this is not possible or available.

As the bulbar muscles of the face are affected, eating and swallowing can become difficult. Due to the weakening of the respiratory muscles breathing can also be labored. It is therefore essential for patients to undergo chest physiotherapy (CPT). CPT is a standard set of procedures designed to trigger and aid coughing in patients. Coughing is important as it clears the patient's lungs and throat of moisture and prevents secondary problems, such as pneumonia.

As symptoms progress, patients may require a ventilator to aid breathing.

Prognosis

The majority of patients with SBMA have a normal life span. About 10% of older, severely affected patients with SBMA may die from pneumonia or asphyxiation secondary to weakness of the bulbar muscles.

BOOKS

Zajac, J. D., and H. E. MacLean. "Kennedy's Disease: Clinical Aspects." Genetic Instabilities and Hereditary Neurological Diseases, edited by R. D. Wells and S. T. Warren. New York: Academic Press, 1998, pp. 87-100.

PERIODICALS

Crawford, T. O., and C. A. Pardo. "The Neurobiology of Childhood Spinal Muscular Atrophy." Neurobiology of Disease 3 (1996): 97-110.

Ferlini, A., et al. "Androgen Receptor CAG Repeat Analysis in the Differential Between Kennedy's Disease and Other Motoneuron Disorders." American Journal of Human Genetics 55 (1995): 105-111.

ORGANIZATIONS

Kennedy Disease (SBMA) Support Group. 1804 Quivira Road, Washington, KS 66968. (785) 325-2629. gryphon@grapevine.net. <http://www.geocities.com/HotSprings/Villa/1989>.

National Ataxia Foundation. 2600 Fernbrook Lane, Suite 119, Minneapolis, MN 55447. (763) 553-0020. Fax: (763) 553-0167. naf@mr.net. <http://www.ataxia.org/>.

WEBSITES

The Andrew's Buddies web site. FightSMA.com <http://www.andrewsbuddies.com/news.html>.

Families of Spinal Muscular Atrophy. <http://www.fsma.org>.

Muscular Dystrophy Association. <http://www.mdausa.org>.

Philip J. Young

Christian L. Lorson, PhD