TAR Syndrome

By | June 10, 2022

Under the TAR syndrome, English thrombocytopenia-absent radius syndrome, medicine understands a malformation syndrome, the main symptoms of which include the non-formation of the spokes and thrombocytopenia. The cause of the syndrome is believed to be an inherited gene mutation. In the first few years of life, treatment consists mainly of platelet transfusions.

What is TAR Syndrome?

TAR syndrome is a complex of multiple malformations that manifests in neonatal life. The main symptoms of the hereditary malformation syndrome are a bilateral non-formation of the radius and a lack of blood platelets. Because of the symptoms, the syndrome is sometimes also referred to as radial aplasia-thrombocytopenia syndrome. The TAR syndrome has so far been described in just over 100 cases. An exact prevalence is not known, but the symptom complex is considered relatively rare. For what is kasabach-merritt syndrome, please visit gradinmath.com.

The syndrome was first described in 1929. The Americans HM Greenwald and J. Sherman are the first to describe it. According to previous documentation, women are affected somewhat more frequently by the malformations than men. Because of its rarity, the syndrome has not been fully researched. Research into the causes has provided partial success, but so far has not been able to provide a sufficient explanation for the overall complex.


In 2007, a possible cause of TAR syndrome was identified, which corresponds to a genetic mutation. Partial symptoms of the complex are caused by a microdeletion on chromosome 1 in gene locus q21.1. In this context we are talking about the 1q21.1 deletion syndrome. Chromosome 1 has been linked to numerous hereditary diseases.

For example, mutations at this gene locus can trigger Usher syndrome, Gaucher disease or Alzheimer’s disease. Chromosome 1 is present in all body cells as a pair of chromosomes and corresponds to the largest human chromosome. The mutation associated with TAR syndrome appears to be necessarily present in all patients. However, the mutation does not adequately explain the individual symptoms of the syndrome.

TAR syndrome is considered a hereditary disease. Familial accumulation has been observed in the cases documented so far. Inheritance appears to be autosomal recessive with relatively large manifestation variability.

Symptoms, Ailments & Signs

All patients with TAR syndrome suffer from thrombocytopenia. The lack of platelets leads to an increased tendency to bleed. They decrease, especially in the first two years of life. In the first few months, intracranial bleeding can occur, which can promote motor or mental retardation. Bilaterally, all patients with the syndrome also lack spokes.

The thumb of those affected is present but functions abnormally. There is often a radial deviation of the hand, which manifests itself as a club hand deformity. The ulna of all TAR patients is shortened and partially bent. About a third of patients are missing the humerus, which is usually also shortened and appears dysplastic. The mobility of the elbow, shoulder and hand joints is restricted.

In some cases, there are also changes in the blood. In two thirds of the cases, strongly increased leukocytes occur. Cow’s milk allergy or intolerance, which promotes diarrhea or exacerbates thrombocytopenia, is often an accompanying symptom. In about half of all patients, the symptoms are associated with dysplasia of the lower extremities.

Hip dysplasia, coxa valga, knee joint subluxation or patellar dysplasia with dislocation are particularly common symptoms. The knee may be stiff. The foot and toe positions are often abnormal. Many of those affected also suffer from short stature or a heart defect in the sense of tetralogy of Fallot or an atrial septal defect. There is often ptosis or glaucoma in the eye.

Diagnosis & course of disease

In the first few months of life, doctors will observe a tendency to bleed and thrombocytopenia in TAR patients, which they must differentiate from Fanconi anemia in the differential diagnosis. In X-ray imaging, the TAR syndrome manifests itself above all in the bilateral non-alignment of the spokes and the resulting misalignments.

In terms of differential diagnosis, Holt-Oram syndrome and Roberts syndrome must also be considered. Once the first two years of life are over, the prognosis for patients with TAR syndrome is rather favourable. In individual cases, the prognosis depends on accompanying symptoms such as the heart defect.


Various malformations occur in TAR syndrome. First and foremost, the malformations lead to a significantly increased tendency to bleed. Even with very slight and small injuries, those affected suffer from heavy bleeding, which cannot be stopped easily. Bleeding in the gums or in the nose often occurs and has a very negative effect on the quality of life of those affected.

Furthermore, mental retardation can occur due to the TAR syndrome. The patients are very often dependent on the help of other people in their lives and cannot do many things of everyday life on their own. The mobility of the shoulders and hands is also significantly restricted by the syndrome, since the humerus is missing. It can also lead to a heart defect or problems with the eyes.

The syndrome is usually associated with a reduced life expectancy. Parents or relatives often suffer from psychological problems or depression. In the symptomatic treatment of the TAR syndrome, as a rule, no complications arise. Unfortunately, not all complaints can be completely limited.

When should you go to the doctor?

In most cases, those affected with TAR syndrome need medical evaluation and treatment. Self-healing is not possible, so the person affected with this disease always has to rely on a medical diagnosis. The earlier the syndrome is recognized, the better the further course of this disease. Since it is a hereditary disease, it cannot be completely cured. If the person affected by the syndrome wishes to have children, genetic counseling can also be used.

A doctor should be consulted for TAR syndrome if the person affected suffers from severe mental retardation. As a rule, the patients depend on the help of their fellow human beings in their lives. The mobility of the affected person can also be limited by the TAR syndrome, so that a visit to a doctor is necessary. It is not uncommon for the internal organs to be affected by various defects. The diagnosis of TAR syndrome can be made by a general practitioner or paediatrician. For further treatment, a visit to a specialist is necessary.

Treatment & Therapy

The TAR syndrome can neither be causally nor specifically treated. So far, only symptomatic treatments are available. The malformations cannot be corrected in the first years of life due to the tendency to bleed. In later stages of life, reconstructive surgical interventions can correct the missing spokes and the multiple deformities. Prevention of any bleeding or haemorrhage during the first years of life is essential.

The goal of the initial therapy is primarily the reduction of significant consequences of the disease. Severe thrombocytopenia in the first years of life call for platelet transfusions. In and of itself, there is no motor developmental disorder. Neurological limitations are also a rarity. Mental development is unremarkable. Thus, all retardations are at best a consequence of intracranial bleeding, which should be prevented by transfusions.

When the thrombocytopenia has resolved, the plastic surgical treatment measures are carried out. These measures are accompanied by [[[physiotherapy|physiotherapeutic treatment steps]], which are intended to ensure flawless motor development. In adulthood, the patients are often no longer dependent on any treatment measures and lead a largely normal life with an unrestricted quality of life.


The definitive causes of TAR syndrome have not yet been elucidated. For this reason, the syndrome cannot be prevented so far. However, all indications are that genetic factors play a role in the syndrome. Therefore, genetic counseling of those affected can largely be described as a preventive measure.


Follow-up care for TAR syndrome depends on the type and severity of the malformations. After an operation, which is an option for minor deformities, the patient requires comprehensive follow-up care. In the case of acute bleeding, immediate care in the hospital is necessary. The patient then needs rest for a few days.

A final follow-up examination aims to determine further treatment measures. People who suffer from TAR syndrome must consult the doctor regularly to clarify their current state of health. In the case of internal bleeding in particular, medical complications are not always apparent to the patient. Severe thrombocytopenia may require a blood transfusion, which takes place in the clinic and is usually associated with a follow-up discussion.

The patient, in turn, needs rest and protection. Hospitalization is usually indicated. Patients suffering from TAR syndrome need a specialist doctor. The doctor in charge is usually the internist or general practitioner who is already involved in the treatment. In the case of chronic complaints, long-term accommodation in a clinic makes sense. The patient should also contact a physiotherapist and other specialists. Psychological care of the patient may also be necessary.

You can do that yourself

The TAR syndrome can only be treated symptomatically. The patient must be alert to warning signs and inform the doctor so that a blood transfusion can be performed early. After such a transfusion, the body is weakened and it is important to ensure a balanced diet that supports the body in blood formation.

Rest and bed rest apply after surgical treatment of the malformations. The patient must take care of the wounds according to the doctor’s instructions to avoid inflammation and other complications. In the case of deformities in the limbs, physiotherapeutic treatment may also be necessary. Affected people can do physiotherapy at home and improve the coordination of the affected limbs with regular exercise.

If these measures do not achieve the desired result, it is necessary to consult the doctor. Since the TAR syndrome is an extremely rare condition, a specialist doctor must take over the therapy. It’s a good idea to search internet forums for other sufferers, as few self-help groups exist for the condition. Finally, it is important to make use of the necessary visits to the doctor in order to avoid serious complications. TAR syndrome needs to be closely monitored due to possible blood transfusions.

TAR Syndrome