TAR syndrome is a rare, inherited disease of the blood and bones. A baby with TAR is born without a radial bone and with a low number of platelets in the blood (thrombocytopenia), which increases the risk of life-threatening bleeding into the brain in the first years of a baby's life. What are the causes and symptoms of TAR? What is the treatment?

TAR syndrome , also known as the syndrome of thrombocytopenia and radial aplasia, or congenital hypoplastic thrombocytopenia, is a rare, genetically determined syndrome of congenital abnormalities consisting of a bilateral lack of a radius bone (one of the forearm bones), low blood platelet count (thrombocytopenia) and other defects.

TAR syndrome - causes

Most patients with TAR suffer from a mutation in one copy of the RBM8A gene and the absence of a specific DNA fragment (deletion) in chromosome 1q21.1 that contains the second copy of the RBM8A gene. A small number of people affected by this disease have a mutation in both copies of the RBM8A gene, but do not have a deleted DNA fragment on chromosome 1q21.1.

TAR is inherited in an autosomal recessive manner, i.e. a child must receive one copy of the defective gene from each parent to get the disease.

TAR syndrome - symptoms

In the TAR syndrome, there is no deformation of the radius, but only its buds (aplasia). In addition, the ulna is shortened, although it may also be missing. As a result, the hands are very short, and the hands (patients usually have all fingers) grow straight out of the arms. In addition, the humerus may be shorter than that of a he althy child and placed crosswise. The patient may also struggle with other defects of the osteoarticular system, usually of the lower limbs.

About half of patients with TAR syndrome are allergic to cow's milk, which may worsen symptoms of thrombocytopenia

The second inherent element of TAR syndrome is thrombocytopenia (the body does not produce enough platelets), which prevents the blood from clotting normally, which is manifested by bruising on the skin, easy bruising, frequent bleeding from the nose, gums, mucous membranes, as well as bleeding after even the smallest injuries. However, episodes of thrombocytopenia decrease with age and the platelet count may return to normal before reachingadulthood.

Due to thrombocytopenia, bleeding inside the body, eg into the brain, which may be life-threatening, may also occur. The risk of such bleeding is high, especially in the first year of life, and may lead to the child's death or mental disability.

In addition, people with TAR syndrome may also have other birth defects, for example, of the heart or the genitourinary system (kidney anomalies, agenesis - i.e. undergrowth - of the uterus, cervix and upper vagina). People with TAR syndrome may also have facial deformities - abnormally small jaw (micrognation), low-set ears, high and wide forehead.

TAR Team - diagnosis

Diagnosis is made by symptoms and genetic testing. At the time of diagnosis, the physician should rule out other genetic diseases such as RAPADILINO syndrome, Edwards syndrome, Roberts syndrome, and the VACTERL association.

TAR syndrome - treatment

The patient must have regular platelet levels monitored and, if necessary, platelet transfusions are performed. In adults who are still struggling with thrombocytopenia, splenectomy can be performed, which removes part of the spleen (and therefore removes the main site where platelets are destroyed). However, as shown by doctors, 30-40 percent. patients do not respond to splenectomy or have recurrent thrombocytopenia.

People with TAR should avoid trauma, even the smallest ones, and certain anti-platelet medications (e.g., non-steroidal anti-inflammatory drugs), as this can lead to bleeding.

If a radius is missing, an operation can be performed to straighten and stretch the wrist and forearm to extend the arm.

TAR team - prognosis

The first two years of life are decisive for the TAR team. This is the time when your baby is most at risk of life-threatening bleeding - especially in the brain. Additionally, people with TAR may have an increased risk of developing acute leukemia in childhood or adulthood.

Category:

Genetic diseases