Thrombocytopenia-absent radius syndrome is a rare congenital condition. It causes a low platelet count and the absence of the radius bone in both forearms.
Thrombocytopenia occurs when the number of platelets in your blood is too low. Platelets help your blood to clot, so people with thrombocytopenia have a higher chance of bleeding events.
Thrombocytopenia-absent radius syndrome is a rare condition where a person has thrombocytopenia as well as the absence of certain bones in their forearm. People with this condition can also have other skeletal and health problems.
This article provides more information on thrombocytopenia-absent radius syndrome, including its symptoms, what causes it, and how it’s treated.
Thrombocytopenia-absent radius (TAR) syndrome is a rare congenital condition. Only
There are two characteristic features of TAR syndrome. These are thrombocytopenia and specific skeletal irregularities.
In people with TAR syndrome, the cells that develop into platelets are defective or don’t develop properly. This leads to thrombocytopenia, or low platelet levels, which can result in serious, potentially life threatening bleeding events.
The characteristic skeletal irregularity of TAR syndrome is the absence of the radius bone on both sides of the body. The radius is a long, thin bone in the forearm. It extends from your elbow to the thumb side of your wrist.
Pictures of thrombocytopenia-absent radius syndrome
The symptoms of TAR syndrome, as well as their severity, can vary from person to person. Below are the different characteristics of TAR syndrome and their individual traits and symptoms.
Symptoms of thrombocytopenia can include:
- bleeding, even from minor injuries, that takes a long time to stop
- bleeding under your skin, which may be in the form of petechiae or purpura
- frequent nosebleeds
- bleeding gums
- blood in your stool or urine
- menstrual periods that are longer or heavier
As well as the absence of the radius bone on both sides of the body, people with TAR syndrome may have additional skeletal differences. These can include:
- underdevelopment of the:
- ulna, which is the other bone in the forearm
- humerus, which is the bone of the upper arm
- fused fingers or curved pinky fingers
- lower limb irregularities, such as:
- a loose or absent kneecap
- inward rotation of the leg bones
The skeletal differences associated with TAR syndrome can lead to reduced upper body strength and mobility issues. Due to this, they can have a big impact on function and quality of life.
Additional signs and symptoms
Additional findings in people with TAR syndrome can include:
TAR syndrome is a genetic condition. It’s caused by changes in a gene called RBM8A.
TAR syndrome passes down an autosomal recessive way. This means that you have to receive two copies of the faulty gene, one from each parent, to have TAR syndrome.
Some people only receive one faulty RBM8A gene. However, the healthy copy of the gene from the other parent is lost through a deletion that happens during development. Because only the faulty gene remains, it results in TAR syndrome.
Your chance of TAR syndrome is increased if there’s a history of it in your family. However, there are
Treatment of thrombocytopenia can involve receiving platelet transfusions. A doctor may also recommend avoiding cow’s milk, as this may trigger an episode of thrombocytopenia in some people.
Skeletal irregularities are manageable with a variety of assistive devices to help with mobility and independence. These can include splints, braces, prostheses, and mobility aids like wheelchairs. Physical therapy may also be beneficial.
If congenital heart disease is present, surgery may be necessary to correct it.
Thrombocytopenia in people with TAR syndrome typically develops within the
Severe bleeding events are the most common cause of death in children born with TAR syndrome. This most commonly occurs
Platelet count typically
TAR syndrome is a rare congenital condition that’s characterized by low platelet counts and the absence of the radius bone on both sides of the body.
People with TAR syndrome may have other skeletal or health problems as well.
The effects of TAR syndrome are manageable with platelet transfusions and assistive devices. Platelet count typically increases with age, lowering the risk of potentially life threatening bleeding events.