Diseases

Thiamine responsive megaloblastic anemia syndrome

A rare genetic disorder characterized by megaloblastic anemia, hearing loss and diabetes. The condition is caused by a deficiency of a thiamine (vitamin B1) transporter protein which means that the body is unable to effectively utilize thiamine from the diet.

Thies Reis syndrome

A rare condition characterized by hearing loss caused by fixation of stapes (ear bone which causes conductive deafness if it becomes fixed and immovable). It can occur as a result of various bone diseases or even chronic ear infections

Thiolase deficiency

A rare syndrome involving a deficiency of an enzyme called thiolase which results in mental retardation and muscle problems.

Thiopurine S methyltranferase deficiency

Thiopurine methyltransferase or thiopurine S-methyltransferase (TPMT) is an enzyme (EC 2.1.1.67) that methylates thiopurine compounds. The methyl donor is S-adenosyl-L-methionine, which is converted to S-adenosyl-L-homocysteine. This gene encodes the enzyme that metabolizes thiopurine drugs via S-adenosyl-L-methionine as the S-methyl donor and S-adenosyl-L-homocysteine as a byproduct. Thiopurine drugs such as 6-mercaptopurine are used as chemotherapeutic agents. Genetic polymorphisms that affect this enzymatic activity are correlated with variations in sensitivity and toxicity to such drugs within individuals. A pseudogene for this locus is located on chromosome 18q

Thomas syndrome

Another name for Dejerine-Sottas disease (or close medical condition association). An inherited, progressive, hypertrophic nervous system disorder which affects limb function

Thoracic celosomia

A rare malformation where the organs inside the chest protrude through an abnormal opening in the chest wall.

Thoracic Insufficiency Syndrome

Thoracic insufficiency syndrome may result from a primary chest wall problem and/or from scoliosis. This can become so significant at a young age that it can impact normal lung development and growth which can affect the function of the chest in moving air in and out of the lungs.

Thrombocytopenia Robin sequence

A very rare syndrome characterized by a variety of abnormalities such as short stature, unusual hair, reduced blood platelets, heart defects and tooth enamel anomaly.

Thrombocytopenia X-linked

A mild inherited form of thrombocytopenia which is a blood clotting disorder caused by a reduced number of normal blood platelets.

Thrombocytopenia- cyclic

Cyclic thrombocytopenia (medical condition): A rare disorder characterized by periodic fluctuations in blood platelet levels.

Thrombocytopenia-absent radius (TAR) syndrome

is a rare condition in which thrombocytopenia is associated with bilateral radial aplasia. TAR syndrome was first described in 1951. An autosomal recessive inheritance pattern was proposed because TAR affected more than one member of some families. In 1969, TAR was defined as a syndrome and further classified as the association of hypomegakaryocytic thrombocytopenia and absent radii. The expression varies and includes abnormalities in the GI, skeletal, hematologic, and cardiac systems. 

http://reference.medscape.com

Thrombomodulin anomalies- familial

A defect in a protein involved with anticoagulation which results in an increased risk of developing blood clots which can result in death.

Thrombotic thrombocytopenic purpura- acquired

Thrombotic thrombocytopenic purpura (TTP) is a rare blood disorder. In TTP, blood clots form in small blood vessels throughout the body.

The clots can limit or block the flow of oxygen-rich blood to the body's organs, such as the brain, kidneys, and heart. As a result, serious health problems can develop.

The increased clotting that occurs in TTP also uses up platelets (PLATE-lets) in the blood. Platelets are blood cell fragments that help form blood clots. These cell fragments stick together to seal small cuts and breaks on blood vessel walls and stop bleeding.

With fewer platelets available in the blood, bleeding problems can occur. People who have TTP may bleed inside their bodies, underneath the skin, or from the surface of the skin. When cut or injured, they also may bleed longer than normal.

"Thrombotic" (throm-BOT-ik) refers to the blood clots that form. "Thrombocytopenic" (throm-bo-cy-toe-PEE-nick) means the blood has a lower than normal number of platelets. "Purpura" (PURR-purr-ah) refers to purple bruises caused by bleeding under the skin.

Bleeding under the skin also can cause tiny red or purple dots on the skin. These pinpoint-sized dots are called petechiae (peh-TEE-kee-ay). Petechiae may look like a rash.

TTP also can cause red blood cells to break apart faster than the body can replace them. This leads to hemolytic anemia (HEE-moh-lit-ick uh-NEE-me-uh)—a rare form of anemia. Anemia is a condition in which the body has a lower than normal number of red blood cells.

A lack of activity in the ADAMTS13 enzyme (a type of protein in the blood) causes TTP. The ADAMTS13 gene controls the enzyme, which is involved in blood clotting. The enzyme breaks up a large protein called von Willebrand factor that clumps together with platelets to form blood clots.

Types of Thrombotic Thrombocytopenic Purpura

The two main types of TTP are inherited and acquired. "Inherited" means the condition is passed from parents to children through genes. This type of TTP mainly affects newborns and children.

In inherited TTP, the ADAMTS13 gene is faulty and doesn't prompt the body to make a normal ADAMTS13 enzyme. As a result, enzyme activity is lacking or changed.

Acquired TTP is the more common type of the disorder. "Acquired" means you aren't born with the disorder, but you develop it. This type of TTP mostly occurs in adults, but it can affect children.

In acquired TTP, the ADAMTS13 gene isn't faulty. Instead, the body makes antibodies (proteins) that block the activity of the ADAMTS13 enzyme.

It's not clear what triggers inherited and acquired TTP, but some factors may play a role. These factors may include:

  • Some diseases and conditions, such as pregnancy, cancer, HIV, lupus, and infections

  • Some medical procedures, such as surgery and blood and marrow stem cell transplant

  • Some medicines, such as chemotherapy, ticlopidine, clopidogrel, cyclosporine A, and hormone therapy and estrogens

  • Quinine, which is a substance often found in tonic water and nutritional health products

Thymic Carcinoma

Thymic carcinoma, or type C thymoma, is a malignancy of the thymus. It is a rare cancer that is often diagnosed at advanced stages. Recurrence following treatment is common, and thymic carcinoma is associated with a poor prognosis.

A study examining cases of thymic carcinoma in the United States from 2001 to 2015 found a peak incidence from 70 to 74 years old and a higher incidence in males compared to females. After thymoma, thymic carcinoma is the second most common type of thymus cancer

Thymidine Kinase 2 Deficiency

Thymidine kinase 2 deficiency (TK2D) is a rare genetic mitochondrial disorder causing progressive muscle weakness (myopathy) that can lead to severe breathing, swallowing, and walking difficulties. It is caused by mutations in the TK2 gene, which disrupts the production of mitochondrial DNA (mtDNA) and impairs energy production in cells, particularly muscles. Symptoms range from mild to severe and can appear at any age, with earlier onset typically resulting in more rapid progression. 

Thyroid cancer- anaplastic

Anaplastic thyroid cancer (ATC) (or undifferentiated) is a form of thyroid cancer which has a very poor prognosis (14% ten-year survival rate) due to its aggressive behavior and resistance to cancer treatments.

Thyroid cancer- familial medullary

Medullary thyroid cancer is completely different than the more common papillary and follicular types. Medullary thyroid cancer is usually not classified in terms of differentiation because it does not arise from the thyroid cells themselves, but rather from the specialized "C-cells" that are in between the thyroid cells. These C-cells are also sometimes referred to as parafollicular cells. They are found mostly in the upper and middle parts of the thyroid and they produce a substance called calcitonin which can serve as a marker for medullary thyroid cancer. Although we know that calcitonin is somehow involved in the body's regulation of calcium, we do not know its exact function. We do know that people who have had their thyroids removed surgically, do not require replacement of calcitonin for normal function and a healthy life.