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Undine's curse syndrome: why do healthy children die?
Last reviewed: 05.07.2025
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Infant mortality, seemingly without cause, has been worrying humanity for many hundreds of years. A generally healthy baby falls asleep safely, and then simply stops breathing and dies. This phenomenon is quite common among children in their first year of life. Previously, it was called sudden infant death syndrome, later it received the unofficial name "Ondine's curse syndrome".
Perhaps because the percentage of infant mortality due to sudden cessation of breathing during sleep is much higher than in adults, not everyone knows that the pathology can manifest itself at an older age. And the time of development of the disease is very difficult to predict, while the consequences of "breathlessness" can be the most tragic.
Let's figure out what this syndrome is, what its causes are and why it received such an unusual name.
A bit of history
There are many beautiful myths and legends in the world that have come down to us from ancient times and tell of the great power of love, bordering on the terrible power of hatred, the cause of which is most often infidelity and betrayal. Most often, such stories have a tragic end, despite all the romanticism of the situation at the very beginning.
It is this chain of events, based on the above feelings, that formed the basis of the German-Scandinavian legend about the mermaid Undine, who fell in love with an ordinary man. This honor was bestowed upon a young knight named Lawrence, who was so enchanted by his chosen one that he swore an oath of love and fidelity to her, saying that he would be faithful to his beloved as long as he could breathe, waking up in the morning. The beautiful Undine believed the promises of the young man, married him and gave birth to an heir, sacrificing her eternal youth and beauty.
Time passed, the handsome prince's love cooled, and he began to look at younger and more attractive girls, forgetting about his oath. The mermaid's originality, which had once attracted the young man so much, began to irritate him, and he gave preference to ordinary earthly beauties.
One day, Undine saw another girl in the arms of her beloved. She saw before her eyes that happy day when Lawrence swore eternal love, and his words "as long as I can breathe, waking up from sleep in the morning" sounded in her head. Love and hate filled Undine's heart and she cast a curse on the traitor, according to which he would breathe only when he was awake, and when he fell asleep, he would expose himself to the danger of death, since he would not be able to breathe in his sleep. Thus, he would never be able to forget Undine for a minute as long as he lived.
The end of this story is sad. The knight died in his sleep when his breathing stopped. The same fate awaited many babies and adults with Ondine's curse syndrome, who at night stopped breathing, without which human life is unthinkable.
Epidemiology
[ Causes of Undine's curse syndrome
For a long time, medical scientists could not establish a connection between the development of respiratory dysfunction and the state of human health, because healthy babies who were predicted to have a long, happy life died from Ondine's curse syndrome. This confused doctors, and they simply could not explain the cause of what happened to the children's distraught parents.
In the middle of the last century, scientists managed to connect respiratory pathology with nocturnal apnea, which made it possible to consider Ondine's syndrome as one of the types of sleep apnea. But this still did not explain the cause of respiratory depression against the background of excellent health and the absence of pathologies affecting the quality of inhalation or exhalation.
Geneticists have already solved the mystery of this phenomenon in our century. They have discovered a genetic mutation of the PHOX2B gene of chromosome 4p12 in patients with Ondine's curse, which is responsible for the development of the respiratory center in the embryo's brain. The mutation causes certain disorders in the respiratory function, which is the cause of Ondine's curse syndrome, which has long been considered inexplicable.
Ondine syndrome, fortunately, is not hereditary. But on the other hand, it is even more difficult to predict, because the reasons for the gene mutation remain a mystery.
Risk factors
But not everyone has Ondine's curse syndrome in infancy. This pathology does not fit into a specific age range. There is no such thing as risk factors to characterize it. Fatal respiratory arrest can occur in anyone at any age, and the main thing here is to provide timely assistance to the patient, thereby saving his life.
There are, however, some minor sexual restrictions for the syndrome. As you remember, Undine's curse concerned her lover, who, as expected, was a representative of the strong half of humanity. So, statistics claim that men are most susceptible to the disease, although cases of the development of pathology in women are not excluded.
According to some studies, it can be stated that every tenth representative of the stronger sex, falling asleep, risks never waking up again due to sudden respiratory arrest. And for men who have crossed the 40-year mark, the likelihood of the onset of symptoms of Ondine's curse syndrome increases 4 times.
Pathogenesis
Breathing is life, and it is very difficult to argue with this statement. Oxygen entering the body during inhalation is the driving force of literally all vital processes. Life simply fades away without it, so after the cessation of breathing, a person usually dies.
Sleep apnea syndrome, which is what Ondine's curse syndrome is called in scientific circles, manifests itself as a short-term ten- to fifteen-second cessation of respiratory function, observed during the process of falling asleep. Each of us has experienced this condition at least once in our lives. Such a short period without oxygen cannot cause serious harm to health or life if it happens rarely. If such respiratory arrests are observed more than 5 times within an hour or become longer, this is a reason to seriously worry about your health, since there is a high risk of developing various pathologies against the background of oxygen starvation and even death in sleep.
The process of breathing, like many other processes in the human body, is carried out automatically and is controlled, as usual, by the brain. From the respiratory center of the brain there is a constant flow of impulses to the respiratory system, and we do not even think about when we need to inhale or exhale. If in a state of wakefulness a person can somehow take this process under his control, then in a dream our breathing is completely automated. This allows us to live at a time when other functions of the body are suppressed to one degree or another.
The danger of Ondine's curse syndrome is precisely that a person, falling asleep, becomes unable to control his breathing. And when the activity of the respiratory center is disrupted, signals from the brain stop coming and breathing stops, the person remains defenseless in a state of sleep, because he does not even realize what is happening to him.
Symptoms of Undine's curse syndrome
As already mentioned, Ondine's curse syndrome is a type of sleep apnea characterized by breathing pauses during sleep. Obstructive apnea, which mainly affects men over 40, is frequent breathing pauses during sleep due to an obstruction of the air flow in the upper respiratory tract. The causes of this condition may be excess weight, anatomically incorrect throat structure, age-related changes in muscle tone, bad habits, heredity, rhinitis, some metabolic diseases, etc.
Central apnea has the same pathogenesis as Ondine syndrome. Breathing stops due to the lack of a signal from the brain. But the causes of the disease are not in a gene mutation, but in severe brain pathologies that arose during intrauterine development or were the result of various diseases and head injuries.
Mixed type apnea is most often diagnosed in infants aged 0 to 1 year and can have one or more causes.
Ondine's curse syndrome is sometimes called congenital pulmonary hypoventilation, the main symptoms of which are cessation of respiratory function (respiratory failure) and hypoxia (oxygen starvation of the brain and the body as a whole).
As with other types of sleep apnea, against the background of sleep breathing disorder and frequent awakenings, accompanying symptoms may develop, such as increased irritability and incontinence, depression, severe fatigue, absent-mindedness, and as a result, decreased performance, headaches due to lack of rest at night. Due to the fear of dying in a dream, a person is afraid to fall asleep, because breathing may not recover in a short time. This exhausts the patient both physically and psychologically.
Respiratory dysfunction in patients with any type of apnea may manifest itself in the form of increased respiratory rate, tachycardia, voice changes, shortness of breath, and cyanosis of the skin. Most often, parents of children with Ondine syndrome noticed that the child stopped breathing and his skin acquired a bluish tint.
There are also some disturbances in the body's autonomic system. The patient has hyperhidrosis, periodic dizziness and fainting associated with heart rhythm disturbances, and disturbances in esophageal peristalsis.
Complications and consequences
If no measures are taken to prevent respiratory arrest in patients with sleep apnea, this threatens not only a fatal outcome. Even if a person remains alive after an attack of suffocation, even a short-term cessation of oxygen supply to the brain can negatively affect his health, especially if such attacks are repeated periodically.
In young patients with Ondine's curse syndrome, this concerns not only the time of night sleep, because even in a waking state, breathing control is not automatic, as in a healthy person. As a result, the patients' blood is not sufficiently saturated with oxygen, but their carbon dioxide levels exceed the norm.
All this cannot but affect the work of the brain and cardiovascular system, although other organs and systems of the body also have a hard time. And yet, first of all, the brain suffers, which without oxygen can withstand a maximum of 4-5 minutes, after which irreversible processes of brain tissue death begin to occur, which cannot but affect the work of the corresponding organs and systems of the body.
The brain starves – the nervous system suffers. As a complication of Ondine syndrome, one can consider the development of neuropsychiatric syndrome, the manifestations of which are considered to be Parkinsonism, dementia and psychosis.
In addition, constant oxygen starvation of the brain leads to a decrease in human performance and learning ability; some children cannot speak for a long time, lag behind their peers in development, and develop insufficiency of various organs.
The heart can survive without oxygen for about half an hour, but this does not mean that a decrease in the level of oxygen in the blood during this time will not affect the work of the cardiovascular system. Experiencing oxygen starvation, the heart muscle tries to fill this gap by contracting vigorously to increase the blood flow. As a result, the vessels contract sharply, thereby contributing to an increase in the pressure of the blood flow on their walls. And an increase in blood pressure already has a negative effect on the condition of patients who experience nausea, headaches, deterioration in health, an increased risk of heart attack and stroke, which is especially scary for older people who experience significant wear and tear of the body.
Diagnostics of Undine's curse syndrome
Since Ondine's curse syndrome does not have its own specific manifestations, and its first signs are similar to other types of apnea, diagnosing this condition is quite difficult. Only a special genetic examination can reveal the presence of a gene mutation in a person, but at present the question is not yet posed in this way.
However, there are various instrumental diagnostic methods for sleep studies that help to exclude or confirm the diagnosis of obstructive apnea.
Polysomnography is sleep monitoring with recording of certain parameters: muscle tone (electromyogram), brain activity (encephalogram), blood oxygen saturation (pulse oximetry study), heart function (electrocardiogram), etc. Such studies are conducted in a sleep clinic, but it is possible to carry out the procedure at home using a special device.
An important role in establishing a diagnosis is played by questioning the patient with a description of all the present symptoms, which is one of the rather informative methods of differential diagnostics. It may be necessary to consult an ENT doctor, as well as conduct some tests.
To exclude respiratory dysfunction due to brain injuries and diseases, various head studies can be performed, such as EEG, EchoEG, ultrasound, MRI, neurosonography in newborns, computed tomography, etc.
Treatment of Undine's curse syndrome
I think even a person who is not versed in medical matters understands that it is almost impossible to correct a gene mutation once the event has occurred. At least, modern science has not yet reached this point. Medicines that provide relief to patients with other types of sleep apnea, particularly obstructive apnea, are not able to help patients with Ondine's curse syndrome. But this does not mean that such people are abandoned to their fate.
Yes, in the old days, when sudden infant death syndrome had no worthy explanation, babies who suddenly stopped breathing were mostly not saved. But science does not stand still, and today it has several effective methods for alleviating the condition of patients with Ondine syndrome.
Some of the first, albeit not very convenient, methods of preventing respiratory arrest were oxygen therapy using a ventilation mask, which the patient had to put on before going to bed, and the use of an artificial lung ventilation device. These methods, despite their effectiveness, have many disadvantages.
Firstly, the bulky equipment requires monitoring such patients in a clinical setting, and children very often spend many years of their lives in hospitals, because sleeping without the equipment is sometimes equivalent to death. Sometimes children are attached to the equipment from birth and cannot do without it throughout their lives, at least during periods of daytime or nighttime sleep.
Secondly, there are certain inconveniences, such as various tubes of the equipment that restrict movement during sleep, which does not allow patients to rest fully. And full sleep is the key to productive work and study.
Thirdly, when using ventilators, various infections cannot be ruled out. The use of such instrumental treatment can also negatively affect the speech of the little patient.
Scientists from a number of European countries, in particular Germany and Sweden, have gone further and developed an innovative method of combating sleep apnea. A minor surgical intervention, which consists of implanting a special "smart" electrode into the phrenic nerve of the brain, provides, if not a cure for patients with sleep apnea syndrome, then a significant relief of their condition without any particular inconvenience.
The patient can move freely, he is not tied to bulky equipment, because the implanted electrode has microscopic dimensions. The electrode itself is a kind of respiratory rhythm stimulator, which, if necessary, sends impulses to the nerve endings of the diaphragm instead of the brain, the diaphragm contracts, and the person begins to breathe again.
Forecast
The prognosis in this case depends on how quickly effective measures were taken to eliminate failures in the respiratory function of the body. Doctors believe that such patients should be operated on as early as possible, as soon as symptoms begin to appear, in order to prevent oxygen starvation of the body and the associated consequences.
Yes, the cost of the innovative device is still very high and unaffordable for many, so children are forced to wait a long time for their turn for a full life, remaining connected to artificial lung ventilation devices. But perhaps science will still manage to find ways to identify mutations in embryos in the near future and somehow eliminate them even before the baby is born. And then the Ondine curse syndrome will become the same legend as the story of the mermaid's love for an ordinary person.