What Is It?
Familial dysautonomia (FD), also called Riley-Day syndrome, is an inherited disorder that affects the nervous system. People who are born with FD have fewer nerve fibers for carrying sensations. For this reason, they have trouble feeling pain, temperature, skin pressure and the position of their arms and legs. They can’t experience taste fully. They also have abnormally low levels of a natural chemical called norepinephrine that helps to relay messages between nerve cells.
In addition, people born with FD have difficulty regulating bodily functions, a condition called dysautonomia. These functions are managed by the autonomic nervous system — the network of nerves that controls such “automatic” functions as breathing and sweating. In people with FD, dysautonomia can affect many vital functions. It can cause difficulties in swallowing, digestion and passing urine. It also can interfere with the control of blood pressure, body temperature and the production of tears to keep the eyes moist. FD primarily affects Jews of Eastern European (Ashkenazi) background. It is a genetic problem that is caused by an inherited mutation, or change, in a gene. A gene is a segment of DNA that directs the production of a particular body protein. Scientists believe they have identified the gene that is related to FD. Researchers think that a mutation in this gene interferes with the body’s ability to produce a key protein necessary for nerves to develop and function normally.
FD only occurs when someone who inherits two copies of the problem gene, one from each parent. If a child inherits only one copy of the FD gene, he or she will be a “carrier” of FD, but will not show symptoms of the illness. A carrier can pass the gene to his or her children.
Doctors estimate that about one out of every 30 Ashkenazi Jews is a carrier of FD. This means that roughly one in every 3,600 children of Ashkenazi families is born with the disorder. In most cases, an FD carrier is unaware of the genetic problem until a close family member — child, sibling, niece or nephew — shows symptoms of the disorder.
Symptoms of FD usually begin during infancy and become worse with age. These symptoms can include:
- Poor sucking, with difficulty swallowing
- Frequent choking and gagging
- Repeated vomiting
- Poor weight gain
- Frequent lung infections caused by food and stomach juices that enter the lungs when the child chokes or vomits
- No flow of tears when the child cries
- Ulcers on the cornea, the clear “window” on the front of the eye
- Fewer taste buds, especially on the front of the tongue
- Skin blotches and excessive sweating, especially when the child eats or becomes excited
- Breath-holding spells that can cause fainting
- Slurred speech or a “nasal” voice
- Delayed development, especially difficulty walking
- Sores (ulcers) on the tongue caused by teeth rubbing against the area
- Decreased sense of pain and body position, which leads to frequent accidental injuries
- Curvature of the spine (scoliosis) and deformed joints
- Abnormally high or low body temperature and blood pressure
- Episodes of abnormally fast, slow or irregular heartbeat
- Loss of bladder control (enuresis)
- Delayed puberty, especially in girls
- Decreased reflexes and muscle tone
- Seizures (convulsions) in about 40 percent of cases
Also, many children with FD have repeated episodes of vomiting. These episodes are called autonomic crises. They can occur every 15 to 20 minutes and can last for more than 24 hours. During these episodes, the child also may have very high blood pressure, a drenching sweat, skin blotches, pain in the abdomen, difficulty breathing and other symptoms.
Your doctor may suspect FD based on your child’s symptoms, your family’s Ashkenazi heritage, and the results of your child’s physical examination. Typical problems your doctor may find during an examination include a smooth glossy tongue, decreased reflex response to tapping on a tendon, and the absence of overflow tears with crying. To help confirm the diagnosis, your doctor may do histamine testing. In this test, the doctor injects a small drop of a natural chemical called histamine under your child’s skin. In children with FD, the injected area does not show the normal reaction of forming a small skin bump, or wheal, and becoming red.
If these findings are positive, your doctor may take a sample of your child’s blood and send it for genetic testing.
Familial dysautonomia is a lifelong problem.
FD cannot be prevented. However, through genetic testing, people of Ashkenazi heritage can find out whether they carry the FD gene before they start a family. A genetic counselor can explain a couple’s risk of having a child born with FD.
In addition, special screening tests for FD are available in a small number of medical centers that focus on FD research. These centers are located in the northeastern United States and in Israel.
There is no way to correct the gene mutation that causes FD. Treatment focuses on relieving a child’s symptoms and preventing complications. Treatments include:
- A feeding tube or a surgical opening in the stomach called a gastrotomy to improve feeding and help to prevent food and fluids from entering the lungs
- Methylcellulose eye drops (Artificial Tears, Tears Naturale, Lacril and other brand names) to moisten the eyes and to prevent ulcers on the cornea
- Medicine to control vomiting, high blood pressure and bladder function
- Surgery to correct scoliosis
- Anticonvulsant drugs to control seizures
- Counseling and psychological support for the child and family
When To Call A Professional
If you have a close blood relative with FD, check with your doctor about the need for genetic testing before you start a family. Also talk to your doctor about the risk of having a child with FD if you and your spouse are both of Ashkenazi heritage.
At one time, almost everyone with FD died during childhood. Now, because of advances in medical care, about 50 percent live to age 30.
Diseases and Conditions Center
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.