The presence of three copies of chromosome 18, rather than the normal two. Children with trisomy 18 syndrome have multiple malformations and mental retardation. They characteristically have low birth weight, small head (microcephaly), small jaw (micrognathia), malformations of the heart and kidneys, clenched fists with abnormal finger positioning, and malformed feet. The mental retardation is profound, and the IQ is too low to even measure. Nineteen out of 20 children with trisomy 18 syndrome die before their first birthday. Also called Edwards syndrome.
- Trisomy 21 syndrome
A common chromosome disorder, often called Down syndrome, due to an extra chromosome number 21 (trisomy 21). The chromosome abnormality affects both the physical and intellectual development of the individual. Trisomy 21 (Down) syndrome is associated with a 45% risk for heart malformations, a lesser risk of duodenal atresia (part of the small intestines is […]
Hydrogen-3, an isotope of hydrogen. Tritium is a long-lived weak emitter of radiation and can be easily incorporated in large molecules such as DNA, and is therefore much used for autoradiography in the laboratory.
A sharply pointed shaft, usually with a three-sided point. A trocar may be used within a cannula, a hollow tube, designed to be inserted into a vein, artery, bone marrow or body cavity. The word trocar is derived from the French “trois” (three) + “carre” (side).
The greater trochanter – A powerful protrusion located at the proximal (near) and lateral (outside) part of the shaft of the femur. The greater trochanter is also called the major trochanter, the outer trochanter, and the lateral process of the femur. The lesser trochanter – A pyramidal prominence that projects from the proximal (near) and […]
A small medicated lozenge designed to dissolve. For example, to soothe the throat as a cough drop. Strictly speaking, a troche should be circular since the word derives from the Greek “trokhiskos” meaning “a little wheel.” Pronounced trOh-key