Familial Dysautonomia (FD)
What is Familial Dysautonomia (FD)?
Familial Dysautonomia - pronounced "dys-auto-NO-mia" - is a genetic disease present at birth in male and female Ashkenazi Jews, primarily causing dysfunction of the autonomic and sensory nervous systems. Dysfunction is a result of an incomplete development of the neurons (nerve fibers) of these systems.
The prognosis of the disease depends on early detection, severity of symptoms, and the individual response to therapeutic treatment for this disorder. Supportive treatment can enhance quality of life and promote better survival.
What are the symptoms of FD?
The lack of tears is the landmark symptom of FD. Children with FD have an absence of overflow tears with emotional crying. That is why a tear appears in the Dysautonomia Foundation's FD logo.
Symptoms displayed by a baby with FD might include:
- High prevalence of breech presentation births
- Poor muscle tone - "Floppy Baby"
- Weak or absent suck
- Respiratory congestion due to misdirected swallowing
- Blotching of skin
- Difficulty in maintaining temperature
Symptoms in an older child with FD might include:
- Delay in developmental milestones such as walking and speech
- Poor balance and unsteady gait
- Scoliosis (spinal curvature). 90% of children with FD have scoliosis before 13 years of age
- Orthostatic hypotension - extreme drop in blood pressure with change in posture
- Breath holding in early years to the point of fainting
- Episodic vomiting
- Excessive drooling and sweating
- A smooth tongue and decrease in sense of taste
- Inappropriate temperature control with very high to very low temperatures
- Poor weight gain and growth
- Frequent lung infections
- Decreased reaction to pain or no reaction at all
- Cold, puffy hands and feet
- Extremes in blood pressure
- Corneal abrasions and dry eyes
- Gastric dysmotility
- Dysautonomic "crisis"
A crisis is an incident of extreme physiologic response of the FD child’s body to stress. This stress may be triggered by something physical, such as an infection, or by something causing emotional stress, such as an upcoming medical exam. Whatever the catalyst, the child will become nauseated, usually accompanied by retching or vomiting, have a marked increase in blood pressure, sweating, drooling, increased heart rate, and blotching of the skin. Irritability and a negative personality change accompany these symptoms. Episodes can occur as frequently as daily; some patients will never experience a "crisis."
- Not all children with FD have the same symptoms. The number and severity of symptoms are extremely variable. FD patients can be expected to function independently if treatment is begun early and major disabilities avoided.
- FD children are usually of normal intelligence. There has been an increased frequency of learning disabilities in FD children, however. Early intervention and aggressive therapy in areas of language and learning have been extremely successful in prevention and treatment.
How is FD inherited?
It is estimated that one in 27 individuals of Eastern European Jewish ancestry is a carrier of the gene for FD. All parents of children with FD are carriers of the defective recessive gene that transmits the disease. A parent has no symptoms or warning signs of being a carrier. For individuals who have not been screened for the FD trait, the first clue that they are carriers is the birth of a child with FD.
How is FD diagnosed?
The diagnosis can be made through genetic testing or clinical evaluation. The clinical diagnosis of FD is based upon a constellation of criteria:
- Parents of Ashkenazi Jewish Background
- Absence of fungiform papillae on the tongue [Compare NORMAL and FD tongue images].
- Decreased deep tendon reflexes
- Lack of an axon flare following intradermal histamine
- No overflow tears with emotional crying
A definitive diagnosis can be made with a blood test that will show mutations in the IKBKAP gene in an affected individual. Over 99% of affected individuals will have two copies of the most common mutation.
Genetic testing -- Is there a prenatal or carrier test for FD?
Thankfully, there are prenatal and carrier tests for FD for the general population.
FD was once thought of as a fatal childhood disease, with most children expected to live, on average, only to five years of age. Advances in treatment have dramatically extended life expectancy, but children with FD still suffer from chronic and often debilitating symptoms that prevent them from leading normal lives.