Diseases

Tetrahydrobiopterin deficiencies

Tetrahydrobiopterin deficiency (also known as BH4 deficiency) is a rare disorder that increases the blood levels of phenylalanine. Phenylalanine is an amino acid obtained through the diet. It is found in all proteins and in some artificial sweeteners. If tetrahydrobiopterin deficiency is not treated, excess phenylalanine can build up to harmful levels in the body, causing mental retardation and other serious health problems. High levels of phenylalanine are present from infancy in people with untreated tetrahydrobiopterin deficiency. The resulting signs and symptoms range from mild to severe. Mild complications may include temporary low muscle tone. Severe complications include mental retardation, movement disorders, difficulty swallowing, seizures, behavioral problems, progressive problems with development, and an inability to control body temperature.

Tetraploidy

Tetraploidy: A very rare chromosomal disorder which results in various abnormalities. Infants are usually stillborn or die within months of birth.

Tetrasomy X

A rare chromosomal disorder which causes mental retardation, small head and various other anomalies.

Thakker Donnai syndrome

Thakker-Donnai syndrome: A very rare, severe genetic syndrome characterized by abnormal internal organs and facial anomalies.

Thalamic syndrome

Thalamic syndrome (or thalamic pain syndrome) is a condition that can be associated with inadequate blood supply from the posterior cerebral artery.Thalamic Syndrome (Dejerine-Roussy) is a rare neurological disorder in which the body becomes hypersensitive to pain as a result of damage to the thalamus, a part of the brain that affects sensation. The thalamus has been described as the brain’s sensory relay station. Primary symptoms are pain and loss of sensation, usually in the face, arms, and/or legs. Pain or discomfort may be felt after being mildly touched or even in the absence of a stimulus. The pain associated with thalamic syndrome may be made worse by exposure to heat or cold and by emotional distress. Sometimes, this may include even such emotions as those brought on by listening to music.

Thanatophoric dysplasia- type 1

Thanatophoric dysplasia, type 1: A rare lethal genetic disorder characterized by severe skeletal abnormalities, flat vertebrae, large head and low nasal bridge.

Thanatophoric dysplasia- type 2

Thanatophoric dysplasia, type 2: A rare lethal genetic disorder characterized by severe skeletal abnormalities, flat vertebrae, large head and low nasal bridge

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.