A: Kennedy's Disease (also known as Spinal Bulbar Muscular Atrophy, SBMA, or Kennedy's Syndrome) is a rare and currently incurable and non-treatable X-linked recessive genetic progressive neuro-muscular disease. Both the spinal and bulbar neurons are affected causing muscle weakness and wasting (atrophy) throughout the body which is most noticeable in the extremities (legs/arms), it is also especially noticeable in the face and throat, and causes speech and swallowing difficulties, along with major muscle cramps as well as other symptoms.
Q: What are some of the symptoms of Kennedy’s Disease?
A: See the following link: Symptoms
When do you first start seeing signs of the disease?
A: Generally, symptoms begin to appear in the late 20’s or early 30’s. However, there have been cases where the symptoms showed up in the late teens or as late as in the 60’s.
Who gets Kennedy’s Disease?
A: Kennedy's Disease is a genetic disease, passed on from generation to generation in a family. It is an X-linked recessive inherited gene. Generally males who inherit the gene exhibit symptoms, while females who inherit the gene are usually just carriers. In rare instances, females may also exhibit symptoms.
Is there a treatment or cure for Kennedy’s Disease?
A: Currently there is no treatment or cure. Recent research, however, shows some promising signs. IGF-1 and ASC-J9 are both being tested to determine if they are safe for clinical trials.
What causes the symptoms?
A: The primary symptom of KD, muscle weakness, is due to the death of muscle cells. The loss of these cells means that there are fewer muscle cells to contract and thus the contraction of the muscle is weaker.
What causes the muscle cells to die?
A. The direct cause of the muscle cell death is believed to be the death of the nerve cells that control the contraction of the muscle cells. These nerve cells are known as motor neurons. Motor neurons are the cells that connect the brain to the muscle cells. When you wish to contract a muscle to pick up a pencil, for example, your brain sends signals to the motor neurons that control those muscles. The motor neurons then convey the signal to the muscle cells and the muscle cells contract, performing the movement that you envisioned in your brain. In KD, the motor neurons die and so the connection from the brain to the muscle cells is broken. As a direct result of the loss of the motor neuron, the muscle cells die as well. Whenever muscle cells lose their motor neuron, they will usually die. It is generally thought that KD does not directly cause the muscle cells to die although there is some recent evidence that KD may result in some changes in the muscle.
What causes the motor neurons to die?
This is the million dollar question. The straight answer is that we really do not know for sure. There is a lot of evidence that the motor neuron cell death may be due to the inability of the cells in KD patients to adequately recycle proteins and this results in the build up of old, trashy proteins. This build up of trash is believed to somehow be toxic to the cell.
Why can’t the cell recycle proteins?
KD is a genetic disease – this means that KD patients have a defective gene. The function of genes is to tell the cell how to make a specific protein and a cell can only make proteins for which there is a gene. For example, we all have a gene to tell our cells how to make hemoglobin, the protein that carries oxygen in our blood. Without that gene, our cells would not be able to make any hemoglobin. Since we need hemoglobin to live, such an individual would never even be born. However, occasionally, a gene for a specific protein may be changed so that the cells would make an altered form of the protein. This altered protein may still work, but possibly not as well. This is what happens in sickle cell anemia. The hemoglobin gene has been altered and the hemoglobin made does not work as well.
Since KD is a genetic disease, patients with KD must have an altered gene. The gene that is altered is the one that tells the cells how to make the protein known as the androgen receptor (AR). The normal function of the AR is to mediate the actions of testosterone. Without the AR, testosterone would have no effect on a cell. In men with KD, the AR that is made is altered. It still works but sometimes not as well. The current thinking is that the problem with those with KD, however, is that the altered AR cannot be removed by the cell. Typically, once used, the AR is destroyed by the cell. This is done by processes that help remove all proteins. Even worse, when the cell tries to remove the AR, the altered form of AR jams up these cellular processes preventing the cells from removing any proteins. Apparently, the nerve cell must be able to remove proteins to survive, so the overall effect of the jamming is to kill the cells. Much of the research on KD right now involves investigating ways to ‘un-jam’ these protein removal mechanisms and prevent the death of the cell.
How is Kennedy’s Disease diagnosed?
A: Fortunately, there is a simple blood test today that checks a person’s DNA for the defective chromosome. Almost any DNA testing laboratory can perform the test. A doctor or nurse can draw the blood and send it off to the laboratory. Test results are normally returned within three-to-six weeks. See DNA Testing and Labs.
Why is Kennedy’s Disease so often misdiagnosed?
A: Until the 1990’s, there was no specific test for Kennedy’s Disease. The most frequent misdiagnosis has been ALS (Lou Gehrig's Disease). Other misdiagnoses that some individuals with Kennedy's Disease have received prior to Kennedy's Disease being determined have been: Spinal Muscular Atrophy III - Kugelberg-Welander, Glycogen Storage Disease, Guillain-Barre, Myasthenia Gravis, and Multiple Sclerosis.
Why don’t we hear much about Kennedy’s Disease?
A: Kennedy’s Disease is considered a rare medical disorder. It is estimated that only 1 in 40,000 individuals worldwide has Kennedy's Disease. However, many go misdiagnosed or undiagnosed for years.
Can the disease be passed on to my children?
A: If the mother is the only carrier of the defective gene: there is a 50% chance of passing the affected gene on to male children (in which case, they would develop symptoms in adulthood). The chance of passing the defective gene on to female children is also 50% (in which case, they would be carriers of the gene, but probably never develop actual symptoms). If the father is the only carrier of the defective gene the chances of passing the defective gene to a male child are 0%. However, it is 100 % certain that the gene will be passed on to a female child, and she will be a carrier of the gene.
One of my parents has the defective gene. I have or am considering having children. Should I be tested or should I have my children tested?
A: This is a question that is asked quite often. Some families have even considered prenatal testing. The KDA recommends that if you have this concern, you should consult with a genetic counselor..
I heard someone mention “Dry Drowning.” What is that and do I have to be concerned that this could happen to me?
A: Dry drowning or laryngospasm, is a common occurrence for many with Kennedy’s Disease. It is the result of a spasm in the adductor muscles - the muscles closing or bringing the vocal folds together. Laryngospasm happens when your voice box or the area of the windpipe below the voice box detects the entry of water or another substance. The vocal folds spasm and the airway shuts down. You may have experienced this if a bug flew down your throat while you were starting to inhale, or if you accidentally inhaled while drinking a glass of water. The vocal cords very immediately and very effectively close. That closure is a benefit to protect the airway, but it makes “breathing in” very difficult. The throat muscles weaken (atrophy) in a person with Kennedy’s Disease. Because of this, it becomes more difficult to swallow or clear the throat. Your can read more about laryngospasm at: Voice Doctor.Net.
I am considering having surgery. Is there any information about Kennedy’s Disease that I should make my doctor or anesthesiologist aware of before hand?
A. Yes, the KDA recommends that you print the information found on our web site and review it with your surgeon. The links and articles provide information and warnings that should be taken into account before surgery. You can review and print relevant information at the following link: Surgery Information.
I have Kennedy’s Disease. Should I carry a medical card in my wallet?
A: Yes. It would be quite helpful for an emergency team to know about your physical condition. You can print a medical card at the following link: Medical Card.
Is there a brochure I can give my doctor on Kennedy’s Disease?
A: A comprehensive easy to read guide on Kennedy's Disease that explains what it is, how it is contracted, what the symptoms are, etc. is available. Click on this link to see the brochure: KDA Brochure