Kennedy’s disease is an inherited motor neuron disease that affects males. It is one of a group of disorders called spinal muscular atrophy (SMA).

Onset of the disease is usually between the ages of 20 and 40, although it has been diagnosed in men from their teens to their 70s. Kennedy’s disease is an x-linked recessive disease, which means the patient’s mother carries the defective gene on one of her X chromosomes. Daughters of patients with Kennedy’s disease are also carriers and have a 1 in 2 chance of having a son affected with the disease.

Early symptoms include:

• Tremor of the outstretched hands
• Muscle cramps with exertion
• Fasciculations (fleeting muscle twitches visible under the skin)

As the disease progresses, individuals may develop:

• Limb weakness which usually begins in the pelvic or shoulder regions
• Weakness of the facial and tongue muscles
• Dysphagia – difficulty swallowing
• Dysarthria – slurring of speech
• Recurrent aspiration pneumonia
• Gynecomastia – excessive enlargement of male breasts
• Low sperm count or infertility
• Non-insulin-dependent diabetes mellitus

Some men with KD may be misdiagnosed to have amyotrophic lateral sclerosis (ALS, also Lou Gehrig’s disease).

Kennedy’s disease is slowly progressive. Individuals tend to remain ambulatory until late in the disease, although some may be wheelchair-bound during later stages. The life span of individuals with Kennedy’s disease is usually normal.

Currently there is no known cure for Kennedy’s disease. Treatment is symptomatic and supportive. Physical therapy and rehabilitation to slow muscle weakness and atrophy may prove helpful.