Familial dysautonomia is a rare inherited disorder that disrupts the development and survival of sensory and autonomic nerves, the nerves responsible for things like feeling pain, controlling blood pressure, regulating body temperature, and coordinating swallowing. It is almost exclusively found in people of Ashkenazi Jewish descent, with an estimated carrier frequency of 1 in 30 in that population. The condition is present from birth and affects nearly every system in the body.
The Genetic Cause
Familial dysautonomia results from mutations in a gene called ELP1. More than 99% of affected individuals carry the same specific mutation: a single-letter change in the gene’s DNA that disrupts how it gets read by the cell. Normally, cells process genetic instructions by cutting out non-coding sections and stitching the remaining pieces together, a process called splicing. The ELP1 mutation causes one of those coding pieces to be skipped entirely, producing a shortened, nonfunctional version of the protein the gene is meant to build.
The ELP1 protein plays a role in diverse cellular functions, including cell migration, adhesion, and internal signaling. When too little of it is produced, sensory and autonomic neurons fail to develop properly or gradually die off over time. Importantly, people who carry only one copy of the mutation (carriers) produce enough functional protein from their one working gene copy to develop normally. The disease only occurs when a child inherits two copies, one from each parent. This is why carrier screening has become standard in Ashkenazi Jewish populations and has reduced the birth rate of affected children.
The carrier rate is not uniform. Among Ashkenazi Jews of Polish descent, the carrier rate is approximately 1 in 18, significantly higher than in Ashkenazi Jews of non-Polish origin, where the rate drops to roughly 1 in 99.
How It Affects the Body
Because the autonomic nervous system controls so many involuntary functions, the symptoms of familial dysautonomia are wide-ranging. Signs are typically present from birth. Newborns often have poor muscle tone, a weak suck, and difficulty feeding. One of the earliest hallmarks is the absence of tears when crying, a feature called alacrima. Another classic finding is the absence of fungiform papillae, the small bumps on the tongue that house taste buds, giving the tongue a smooth appearance.
Reduced sensitivity to pain and temperature is common throughout life. This might sound like a benefit, but it’s dangerous: people with familial dysautonomia can injure themselves or develop infections without realizing it. At the same time, the autonomic side of the disease creates problems with blood pressure regulation, digestion, breathing, and body temperature control. Blood pressure can swing dramatically, dropping when standing (causing dizziness or fainting) and spiking during episodes of stress.
Up to 90% of patients develop scoliosis, which can become severe enough to restrict lung capacity. Abnormal craniofacial development also occurs, contributing to upper airway obstruction and sleep apnea in some individuals.
Autonomic Crises
About 40% of people with familial dysautonomia experience what are called autonomic crises, sometimes described as hypertensive vomiting attacks. During a crisis, the body’s fight-or-flight system essentially fires without restraint, flooding the bloodstream with stress hormones like dopamine and adrenaline. The result is intense, cyclical vomiting (or retching), rapid heart rate, heavy sweating, spiking blood pressure, irritability, and sometimes personality changes. These episodes can last several days.
Common triggers include strong emotions, illness, abdominal discomfort, and a full bladder, though crises sometimes strike without any obvious cause. Management focuses on preventing dehydration and electrolyte imbalances, often using fluids delivered through a feeding tube. Medications that calm the sympathetic nervous system can help shorten or reduce the severity of episodes, and daily preventive medication may reduce how often they occur.
Feeding and Breathing Challenges
Swallowing problems are one of the most consequential features of familial dysautonomia. The sensory nerves that coordinate swallowing and protect the airway are impaired from birth, meaning food and liquids can easily enter the lungs instead of the stomach. Most infants aspirate before they even leave the hospital nursery. The protective reflexes that would normally trigger coughing or gagging when something goes down the wrong way are weakened or absent.
Because of this, approximately 85% of patients have a feeding tube surgically placed into the stomach. This allows for safer hydration and nutrition while significantly lowering the risk of aspiration pneumonia, one of the leading causes of illness and hospitalization in this population.
Breathing is further compromised by the body’s inability to sense low oxygen levels. The oxygen-sensing cells in the carotid body (located in the neck) depend on the same type of sensory neurons that are depleted in familial dysautonomia. As a result, patients have virtually no ventilatory response to low oxygen, meaning their breathing doesn’t automatically speed up the way it should when oxygen drops. They retain some ability to respond to high carbon dioxide levels, but the overall effect is a significantly impaired respiratory safety net.
Eye Health and Vision Loss
The inability to produce tears creates serious, ongoing risks to the eyes. Without a normal tear film to keep the cornea moist and nourished, and with reduced corneal sensitivity that prevents the eye from detecting damage, patients are highly vulnerable to corneal injuries that heal poorly. This combination leads to corneal opacities and visual loss in about 27% of patients.
One promising finding is that the tear glands themselves are not entirely nonfunctional. A clinical trial showed that eye drops containing the drug pilocarpine, which stimulates a specific type of nerve receptor in the tear gland, increased tear production by an average of 311% within 30 minutes. The effect persisted for at least three hours. Side effects were mild: temporary blurred distance vision in about 75% of participants and a mild headache in about 19%. This represents a meaningful option for protecting corneal health.
Managing Blood Pressure Instability
Orthostatic hypotension, a sharp drop in blood pressure upon standing, is a persistent problem. It causes dizziness, lightheadedness, leg cramps, and fainting. Two medications have shown meaningful benefits. Fludrocortisone, which helps the body retain salt and expand blood volume, significantly increases average blood pressure and reduces dizziness and leg cramping. In studies comparing long-term outcomes, patients treated with fludrocortisone had significantly better survival during the first decade of life. In later decades, adding midodrine, a drug that tightens blood vessels, further improved survival.
Diagnosis
Familial dysautonomia is typically suspected based on clinical features present in infancy: absent tears, feeding difficulty, poor muscle tone, and reduced pain sensitivity in a child of Ashkenazi Jewish background. The diagnosis is confirmed through genetic testing, which looks for the specific ELP1 mutation. Because over 99% of affected individuals carry the same mutation, genetic testing is highly reliable and definitive. Carrier testing uses the same approach and is widely available as part of preconception or prenatal screening panels for Ashkenazi Jewish couples.
Life Expectancy and Outlook
Survival has improved substantially over the past several decades thanks to better understanding of the disease, earlier intervention for feeding and respiratory problems, and medications that manage blood pressure instability and autonomic crises. Many individuals now survive into adulthood, though the disease remains serious and requires lifelong, multidisciplinary care. The introduction of population carrier screening has also reduced the incidence of new cases.
Research into treatments that address the root cause, rather than just managing symptoms, has focused on small molecules that can correct the gene’s splicing defect. One such compound, kinetin (a plant hormone), was shown in laboratory studies to restore normal protein production in cells taken from patients with familial dysautonomia. A clinical trial testing kinetin’s safety and tolerability in 15 patients completed in 2019, with the goal of demonstrating that the drug could improve correct splicing of the ELP1 gene in living neuronal tissue.