David Cohen, M.D.·Published 13 August 2004·4 min read
Key points
Familial dysautonomia (FD), also called Riley-Day syndrome, is an inherited disorder that affects the nervous system.
Symptoms of FD usually begin during infancy and become worse with age.
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.
However, through genetic testing, people of Ashkenazi heritage can find out whether they carry the FD gene before they start a family.
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
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
Written and revised by
David Cohen, M.D.
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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.
Diagnosis
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.
Expected Duration
Familial dysautonomia is a lifelong problem.
Prevention
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.
Treatment
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.
Prognosis
At one time, almost everyone with FD died during childhood. Now, because of advances in medical care, about 50 percent live to age 30.
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