Originally published by Harvard Health.
What Is It?
Familial dysautonomia (FD), also called Riley-Day syndrome, is an inherited disorder that affects the nervous system. The nerve fibers of people born with FD don’t work properly. For this reason, they have trouble feeling pain, temperature, skin pressure and the position of their arms and legs. They can’t fully experience taste.
In addition, people born with FD have a hard time 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 called IKBKAP. Scientists believe 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 inherits two copies of the mutated or changed gene, one from each parent. If a child inherits only one copy of the mutated IKBKAP gene from one parent, and one normal gene from the other parent, he or she will be a “carrier” of FD. Although he will not show symptoms of the illness, a carrier can pass the gene to his or her children without ever even knowing that they have it.
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 membrane that covers the colored outside part of the eye
- Fewer taste buds than normal, especially on the front of the tongue
- Red 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
Some children with FD may have repeated episodes of vomiting, called autonomic crises, which 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. These episodes can be triggered by emotional or physical stress such as an infection.
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 which a natural chemical called histamine is injected under your child’s skin. Children who do not have FD will develop a small red skin bump called a wheal at the site of the histamine injection. Children with FD however, do not have the same reaction. If no wheal develops at the histamine site, your doctor may take a sample of your child’s blood and send it for genetic testing to look for the mutated IKBKAP gene.
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 mutated IKBKAP 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
- 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, many live into adulthood..
Dysautonomia Foundation, Inc.
315 West 39th St.
New York, N.Y. 10018
Phone: (212) 269-1066
Fax: (212) 269-2066
National Institute of Neurological Disorders and Stroke (NINDS)
P.O. Box 5801
Bethesda, MD 20824
Phone: (301) 496-5751
Toll-Free: (800) 352-9424
TTY: (301) 468-5981
National Library of Medicine (NLM)
8600 Rockville Pike
Bethesda, MD 20894
Phone: (301) 594-5983
Toll-Free: (888) FIND-NLM (346-3656)
Fax: (301) 496-4450