Prader-Willi Syndrome

Prader-Willi Syndrome is a genetic disorder that causes mental and physical impairments and leads to abnormal eating habits. The condition is rare and affects both men and women.

Prader-Willi Syndrome

What is Prader-Willi Syndrome?

Prader-Willi Syndrome (PWS) is a genetic condition that affects both men and women. It is caused by a genetic defect on chromosome no. 15. The altered gene causes mental and physical handicaps as well as metabolic disorders.

A distinctive feature of Prader-Willi syndrome is the uncontrollable desire to eat, which leads to severe obesity in patients. The disease was named after Swiss doctors Andrea Prader and Heinrich Willi, who first described the symptoms in 1956. The chromosome on which the triggering gene defect is located was found in 1981. Prader-Willi syndrome occurs only rarely, it is estimated that around 350,000 people worldwide are affected. See healthknowing for What is the Definition of Cerebral Hemorrhage.


The cause of Prader-Willi syndrome is a mutation of chromosome 15. There are three different variants, but they all lead to the same symptoms. In 70% of cases, the trigger is the absence (deletion) of part of the paternal chromosome 15.

About 29% have a double version of chromosome 15 from the mother, instead of the usual one from the father and one from the mother. The third very rare variant is a special mutation called an imprinting error.

The genetic modification causes the hormone release in the hypothalamus to be irregular. The resulting undersupply of hormones causes physical and mental disorders.

Symptoms, Ailments & Signs

One of the typical symptoms of Prader-Willi syndrome is congenital muscle weakness (muscular hypotonia). The basic tension of the skeletal muscles is lower than in other people. Those affected are also often less sensitive to pain than other people.

The mental and physical development of those affected is below what would be expected given their age. The Prader-Willi syndrome is associated with a moderate intellectual disability. With this degree of intellectual disability, the mental age is between six and nine years. This corresponds to an IQ of 35 and 49. For comparison: An IQ of 85 to 115 is considered normal.

Another feature of Prader-Willi syndrome is an increased appetite and a disturbed feeling of satiety. Affected people often eat more than they need. Both continuous eating and binge eating are possible. As a result, most people with Prader-Willi syndrome are overweight or obese. Obesity often develops in infancy. Diabetes is another possible symptom of Prader-Willi syndrome.

Those affected typically suffer from an underfunction of the gonads (hypogonadia). You may be infertile as a result. External signs of Prader-Willi syndrome are almond-shaped eyes and a triangular mouth area. Hands and feet are often unusually small – short stature also occurs. In many cases, visual disturbances are also a symptom. Short-sightedness and strabismus or strabismus are particularly common.

Diagnosis & History

The symptoms of Prader-Willi syndrome are different and vary from case to case. Some children are already noticeable as unborn children during pregnancy due to a lack of activity. As infants, they drink little and have limp muscles. The children have almond-shaped eyes and a triangular mouth, they suffer from vision problems, they are often short-sighted or squint.

The hands and feet are smaller than normal, and the overall height is also below average because too little growth hormone is produced in Prader-Willi syndrome. The sexual organs are underdeveloped, with boys often having undescended testicles. Puberty is delayed, sex characteristics are poorly developed, and most people are infertile.

Mental disabilities may exist. Later, around the age of three, an uncontrollable food addiction begins to develop. The children eat everything they can find, including waste. Diagnosis is based on symptoms and various tests, such as blood hormone tests and thyroid tests. A genetic test can be used to determine with certainty whether Prader-Willi syndrome is present.


The complications that are to be expected with Prader-Willi syndrome are primarily due to the severe obesity from which those affected almost always suffer, as well as to the consequences of metabolic diseases, especially diabetes mellitus. Being overweight, which is often very high, can also cause severe orthopedic damage. Early orthopedic damage to the lower extremities is already observed in children.

In particular, the weight-bearing joints of the lower extremities, i.e. the hip, knee and ankle joints as well as the feet, often show signs of overload and wear and tear due to being overweight. Life-threatening complications are to be expected with Prader-Willi syndrome, especially when being overweight causes damage to the blood vessels and internal organs.

Since patients suffering from Prader-Willi syndrome do not have a feeling of satiety, there is also a risk that they will overstretch the stomach until it ruptures. This risk is increased because people do not vomit, feel full, or feel pain when they overeat. The perforation of the stomach often goes unnoticed at first. The patients therefore run the risk of bleeding to death internally as a result of the stomach tears.

Furthermore, in patients suffering from Prader-Willi syndrome, the sleep apnea syndrome can assume life-threatening forms. Sleep apnea is a condition that causes people to stop breathing while they sleep.

When should you go to the doctor?

Babies with Prader-Willi Syndrome need a lot of support during and after birth. Parents should consult the responsible doctor directly so that the necessary examinations and treatments can be carried out at an early stage. Depending on the severity of the condition and the number and severity of the malformations, regular visits to the doctor are then necessary. If there are any unusual symptoms, such as fever, difficulty swallowing or visual problems, the respective specialist must be consulted. In addition to the pediatrician, depending on the symptoms, internists, surgeons, ophthalmologists, ENT specialists and other specialists can also be involved.

The affected child also needs physiotherapeutic support. In the case of severe malformations, a rehabilitation measure is already necessary in the first years of life, which is usually carried out with the mother and the child. If the symptoms get worse, a visit to the pediatrician is necessary. If the malformations lead to an accident or a fall, the best thing to do is to call an ambulance. Psychological counseling is recommended if the condition is having a negative impact on the mental state of the child or family members.

Treatment & Therapy

The treatment of Prader-Willi syndrome depends on the symptoms. Hormone replacement therapy is used because the condition involves reduced hormone secretion. The sooner you start giving hormones, the better the symptoms can be alleviated.

Children with Prader-Willi syndrome usually need comprehensive care and special support. Weight needs to be reduced and food intake controlled. Edible things have to be locked away, as patients with Prader-Willi Syndrome will eat anything they can find, whether it’s edible or not. That means they also eat animal feed, waste or frozen foods. Most symptoms improve when patients lose weight.

Behavioral therapy can help with diet compliance. Physiotherapy helps to improve muscle tone and counteract slack muscles. Speech therapy supports the ability to speak. Eye problems usually require treatment by an ophthalmologist, and vision should be checked regularly. The children have to be mentally encouraged, and it may be necessary to attend special schools.

Sometimes in the further course of Prader-Willi syndrome, heart problems and a curvature of the spine develop, caused by extreme obesity. In addition to weight reduction, orthopedic and internal therapy is also necessary.


You cannot prevent Prader-Willi syndrome because it is genetic. Early diagnosis and rapid therapy are important in order to avoid serious consequential damage from Prader-Willi syndrome.


Prader-Willi syndrome is a genetic chronic disease that cannot be cured. Medical treatment is purely symptomatic. Therefore, aftercare in the classic sense is not possible. However, affected children and adults with Prader-Willi syndrome are life-threatening obesity and other health problems.

For this reason, regular check-ups and intensive dietary care are necessary. These measures are usually ordered and supervised by a pediatrician or general practitioner. The body weight of the affected children or adults is primarily checked. Regular blood tests are also common.

Sometimes urine or stool samples or other tests are also required. The doctor treating you decides on the frequency of check-ups and the necessary aftercare measures. In many cases, affected patients are placed in specialized long-term care facilities that also include medical care.

Apart from that, inpatient stays in rehabilitation clinics are usually necessary in order to develop a therapy concept that suits the patient. At least one or two medical examinations per week are usual in the context of such placements. In the course of obesity therapy, further therapeutic measures may be necessary.

You can do that yourself

Children suffering from Prader-Willi syndrome need permanent support in everyday life. Family members should consult a nutritionist and work with them to create a diet that matches the child’s eating habits. Cognitive behavioral therapy may also be necessary. The child should also not have access to potentially harmful food, waste or inedible products. If the child has eaten something unsuitable, an ambulance should be called.

In order to counteract the usually high emotionality of the child, sport and an open approach are offered as accompanying measures for medical treatment. It is important for the child to have a regular daily routine that must not be deviated from. It is advisable to create a long-term plan in order to enable the child to live as stable a life as possible without sudden changes in everyday life. Sick children need a lot of attention and place great physical and mental demands on their parents. This makes phases of rest and relaxation all the more important for the relatives and acquaintances who take care of the child. A therapist can help to create space and work through mental conflicts.

Parents should keep in close contact with doctors and inform them of any unusual symptoms. A comprehensive therapy concept can enable people suffering from Prader-Willi syndrome to lead a relatively symptom-free life.