A chromosome disorder in females caused by the presence of four X chromosomes rather than the usual two. The disorder is characterized by decreased intelligence (IQ 30 to 80; average 55), speech and behavioral problems, tall stature and reduced fertility. Also known as tetra-X syndrome.
- XXXXX syndrome
A chromosome disorder in females, caused by the presence of five X chromosomes rather than the usual two. It is characterized by decreased intelligence (IQ 20 to 75) and multiple malformations including upward-slanting palpebral fissures (eyeslits), heart defect, and small hands with incurving fifth fingers. It is the most severe extra-X syndrome in females. Also […]
The most frequent sex chromosome complement in human males.
A sweetener that is found in plants and used as a substitute for sugar. Xylitol is called a nutritive sweetener because it provides calories, just like sugar. However, it is less likely than sugar to contribute to dental caries.
- XYY syndrome
A chromosomal disorder that affects males only, caused by the presence of an extra Y chromosome. Symptoms may include increased height, speech delays, learning disabilities, mild to moderate mental retardation, and behavioral disturbance. Also known as polysomy Y syndrome.
- X chromosome
The sex chromosome that is found twice in normal females and singly, along with a Y chromosome, in normal males. The complete chromosome complement consists of 46 chromosomes, including the 2 sex chromosomes, and is thus conventionally written as 46,XX for chromosomally normal females and 46,XY for chromosomally normal males.