Sebastian Syndrome

The Sebastian syndrome is one of the MYH9-associated diseases and is a congenital symptom complex with the main symptom of a tendency to bleed, which is caused by a mutation. Familial clusters have been observed. Long-term therapy is not required for most patients to lead a normal life.

Sebastian Syndrome

What is Sebastian Syndrome?

A number of congenital hereditary diseases that are based on a mutation of the MHY9 gene are known as the group of MYH9-associated diseases. In addition to Fechtner syndrome, May-Hegglin anomaly and Epstein syndrome, Sebastian syndrome also belongs to this group of diseases. This complex of symptoms is characterized by a tendency to bleed. The prevalence for Sebastian syndrome is low. See beautyphoon for What is Metabolic Acidosis.

An estimated 50 people are currently affected by the disease. The proportion of sick men and women is somewhat the same. A demographic accumulation has also not been observed so far. The first description of the Sebastian syndrome took place towards the end of the 20th century. The cases documented at that time were described by Greinacher and colleagues.

The low number of cases since the first description has made research on Sebastian syndrome difficult. Not all tendencies and causes of the syndrome have been conclusively clarified.


Sebastian syndrome does not occur sporadically, but is associated with familial accumulation. The 50 cases described so far have been observed in only ten different families. A genetic disposition is obvious for this reason. Inheritance appears to be autosomal dominant. A mutation has now been identified as the cause of the syndrome. As with all MYH9-associated diseases, this mutation affects the MYH9 gene at gene locus q11.2 of chromosome 22.

The individual diseases of the group differ only in the exact localization, but not in the type of mutation. Within the group as a whole, the mutations are predominantly point mutations. The different localization explains the specific symptoms of the individual syndromes. The MHY9 gene is involved in encoding the heavy chains of non-muscle type IIA myosins.

These proteins are mainly found in blood cells such as monocytes and thrombocytes, but also in the cochlea and kidneys. As a result of the gene mutation, patients with Sebastian syndrome suffer from macrothrombocytopenia, which is characterized by a lack of platelets and the hyperplastic size of the platelets.

Symptoms, Ailments & Signs

Patients with Sebastian syndrome suffer from a complex of symptoms consisting of various clinical features. The most typical symptom is macrothrombocytopenia. The oversized platelets of the patients lead to a platelet deficiency. In addition to the abnormal size, inclusions are often found in the individual platelets, which are made up of leukocytes. Platelets play a key role in the coagulation cascade that closes wounds after injury.

Due to their low platelet count, patients with Sebastian syndrome suffer from a tendency to bleed because their wound closure is worse than average. Her bleeding is very heavy. Patients are often prone to bleeding gums or epistaxis. Women with Sebastian syndrome have significantly heavier menstrual bleeding than healthy women of the same age.

Frequent nosebleeds have also been observed in some patients. The blood loss can also put a strain on the general circulatory system of those affected.

Diagnosis & course of disease

The diagnosis of Sebastian syndrome can only be made using molecular genetic testing. Only DNA analysis can prove the connection with the corresponding gene. Related syndromes can also be ruled out simply by localizing the mutation as part of the gene analysis.

The doctor arranges for the DNA analysis after the anamnesis, if the symptoms give rise to a first suspicion of the group of MYH9-associated diseases. In principle, the prognosis is favorable for patients with Sebastian syndrome. Neither their life expectancy nor their quality of life is particularly limited by the disease. However, blood coagulation is slow during operations and injuries.

For this reason, their risk of bleeding in the context of accidents, for example, is higher than that of healthy people. In operations, there is only a high risk if the disease was not previously recognized.


Sebastian syndrome has a very negative effect on the quality of life of those affected and can significantly reduce it. First and foremost, the syndrome leads to significantly delayed wound healing and thus bleeding more frequently and for longer periods. This can delay and restrict development, especially in children.

The risk of severe bleeding also increases during surgical interventions. Furthermore, those affected very often suffer from bleeding gums and thus possibly also from pain or inflammation. In women, Sebastian syndrome can lead to increased menstrual bleeding, which is usually associated with severe pain.

Frequent nosebleeds can also occur and have a negative impact on the patient’s everyday life. The frequent bleeding leads to a loss of blood, which, if it persists, can lead to circulatory problems. Those affected sometimes suffer from dizziness or fatigue.

Sebastian syndrome is only treated symptomatically. Usually there are no special complications. Bleeding can be stopped with medication. Life expectancy is also not restricted or reduced by the syndrome in most cases.

When should you go to the doctor?

In the case of Sebastian syndrome, a doctor must always be consulted. Since this is a genetic disease, self-healing cannot occur, although the affected person only has a purely symptomatic and no causal therapy available. As a rule, the doctor should be consulted for Sebastian syndrome if the patient shows a greatly increased tendency to bleed. Even minor injuries or minor cuts can lead to very heavy bleeding, and the affected person can lose a large amount of blood.

Heavy bleeding from the gums or very heavy menstrual bleeding can also indicate Sebastian syndrome and should be examined by a doctor. In the case of severe injuries, an ambulance should be called or the hospital should be contacted directly to prevent further complications. The Sebastian syndrome is primarily treated by the general practitioner. In the case of further treatments, the person concerned should always point out the Sebastian syndrome to the doctors.

Treatment & Therapy

Causal therapy options are just as unavailable for patients with Sebastian syndrome as they are for those affected by related diseases. A causal therapy would correspond to a gene therapy. Since this treatment path is currently the subject of medical research, genetic diseases such as Sebastian syndrome are likely to be curable in the future.

At the current time, however, the syndrome is still considered an incurable disease that can only be treated symptomatically. In most cases, Sebastian syndrome does not further restrict patients in their lives. For this reason, as a rule, no therapeutic steps are taken. This applies at least as long as those affected are not involved in accidents and have to survive just as few operations.

Only in the case of severe bleeding due to serious injuries or operations does the lack of platelets have to be compensated for temporarily so that the patient does not bleed to death. Such a compensation is usually carried out by administering a platelet concentrate. After the administration of these concentrates, blood coagulation is similar to that of healthy people, and the risk of any complications is therefore minimized.


Sebastian syndrome is a disease that has only recently been documented. Since only 50 cases in a total of five families have been recorded since the first description, the research situation is very limited.

For this reason, neither all of the influencing factors for the original mutation are known, nor are there any preventive measures. Since there is a high probability of passing on the syndrome in families with cases of Sebastian syndrome, these families can seek molecular genetic advice as part of family planning.


Sebastian syndrome is an incurable disease. So far there is no treatment option. Only symptomatic treatment can be given. There are also a few things that those affected should consider so that they can cope with everyday life and no complications arise. It is very important that victims of injuries see a doctor quickly.

Since the blood of sick people does not clot well, they also have to be careful in the event of accidents. Those affected can lead a relatively normal life with appropriate therapy. Nevertheless, they should maintain close contact with family and relatives in order to be able to call on them for help and support in emergencies.

It is also important that the family and relatives are sufficiently informed about the disease. In emergencies, they can then act appropriately. Those affected who suffer greatly from the disease should visit permanent psychological counseling. It can also be helpful for them to go to a self-help group.

There, those affected can talk to other sufferers about the disease and learn about other possible ways of living with the disease. Those affected do not feel alone with the disease. Sufficient exercise and a balanced and vitamin-rich diet are also very important. This reduces the risk of complications.

You can do that yourself

Sebastian syndrome is currently one of the most incurable diseases. This means that there is only symptomatic therapy. There are a few everyday tips that minimize the health risk.

Patients have poor blood clotting, so it is very important to act quickly in the event of injuries. In the event of accidents, those affected must therefore be particularly careful and the doctors should be informed if an operation is due. If there is a serious injury with profuse bleeding, a platelet balance is needed. This ensures that patients do not lose too much blood. With a platelet concentrate, blood coagulation is similar to that of a healthy person. This reduces the risk of possible complications.

Everyday dealing with the hereditary disease therefore refers to certain precautionary measures that are particularly important in sporting activities. Nevertheless, those affected can live relatively normally without long-term therapy. The inheritance of the rare disease is very likely. It is therefore advisable for those affected to seek detailed advice on family planning. In this context, the main concern is the molecular genetic analysis, which forms the basis for the consultation between doctor and patient.