Familial dysautonomia (FD) is a rare genetic condition that affects the autonomic nervous system. It most often occurs in people with Ashkenazi Jewish or Eastern European Jewish heritage.

Familial dysautonomia (FD) is the result of a rare genetic mutation. People with FD can have difficulties with breathing, salivating, and regulating their body temperatures.

According to the Familial Dysautonomia Foundation, Inc., there are only about 350 people living around the world with FD.

FD most commonly occurs in people with Ashkenazi Jewish or Eastern European Jewish heritage. However, it may occur in anyone whose birth mother and father contribute the necessary genetic variation.

Understanding what FD is and how it’s passed on can help you decide if you want to be genetically tested for this condition before becoming pregnant.

FD is a form of dysautonomia. Dysautonomia is when the autonomic nervous system (ANS) malfunctions, including nerves that regulate involuntary functions in your body, such as body temperature and blood pressure.

FD is also known as Riley-Day syndrome. You can read more about other ANS-related disorders here.

FD is a genetic condition present from birth. It affects the body’s ability to perform basic involuntary life functions like breathing, swallowing, and producing tears.

Familial dysautonomia may worsen over time because of neuronal degeneration.

Although FD affects birth males and females equally, it is primarily found in people with Ashkenazi Jewish or Eastern European Jewish heritage.

Language matters

In this article, we use “birth male and female” to refer to someone’s sex as determined by their chromosomes at the time they’re born.

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Familial dysautonomia can cause many symptoms, but they are often distinguished based on your age.

Infants born with FD may have:

  • weak, ineffective sucking
  • difficulty swallowing
  • poor muscle tone
  • low body temperature
  • delayed milestones and growth

As you age with FD, other signs and symptoms may include:

FD is the result of a genetic variation to the ELP1 gene, which was formerly known as the IKBKAP gene. This particular gene codes for proteins that maintain the health of the autonomic nerves. With this particular gene mutation, these nerves degenerate.

FD is an inherited recessive genetic condition. So, two apparently healthy individuals can have a 25% chance of giving birth to a baby with FD if they are both carriers of the gene variation. (They have a 50% chance of giving birth to a child that is a carrier of the gene, though they may not show any outward signs of FD.)

FD affects approximately 1 in every 3,600 Ashkenazi Jewish births, and somewhere between 1 in 27 and 1 in 32 Ashkenazi Jews is a carrier of the FD gene variation.

Getting diagnosed with FD often involves genetic testing.

A healthcare professional will consider your symptoms and family history to figure out if you might have FD. Doctors may look for:

  • a lack of tears when you cry
  • decreased tendon reflexes when muscles are tapped on
  • an absence of fungiform papillae (raised bumps that contain taste buds) on the tongue
  • no redness or swelling after being given a histamine injection
  • Ashkenazi Jewish or Eastern European Jewish heritage (though this is not required to carry the necessary genetics for FD)

Doctors may also perform a special test called the Schirmer test. For this, filter paper is placed in the corner of the lower eyelid. If less than 10 millimeters (mm) is wet after 5 minutes, this can be a sign that there’s diminished tear production.

Doctors may also perform a test to see if your pupils become smaller when methacholine drops are applied to the eye. While methacholine normally has very little effect on pupils, after about 20 minutes, nearly all people with FD will show a change.

Treatments for familial dysautonomia focus on the symptoms you have, often requiring working with several doctors and specialists.

People with FD may require different treatments based on their daily needs, as well as for any complications of living with the condition. FD can affect people differently, so certain treatments may be needed for one person while others are not.

Potential treatments include:

People with FD may also consider trying to avoid:

  • hot or humid weather
  • having a full bladder

It’s important that people with FD and their families be offered genetic counseling so they can make informed family planning decisions. People with FD who become pregnant should be treated as “high risk” due to possible complications such as blood pressure fluctuations.

Currently, there is no cure for FD. As people with FD get older, their physical and general health tends to worsen.

Approximately 21% of people with FD will also have an intellectual disability or developmental delay.

Additionally, people with FD have a decreased life expectancy.

FD is a rare genetic condition that negatively affects your ANS. It’s most often seen in people with Ashkenazi Jewish or Eastern European Jewish heritage.

People with FD may experience insensitivity to pain, a lack of tears, and unstable blood pressure, among other symptoms.

If your child is showing any signs of FD, speak with their doctor to get appropriate testing. While there’s currently no cure for FD, there are many treatments and supports available to improve quality of life.