Turner Syndrome, named after Dr. Henry Turner who discovered it in 1938 but also referred to as ullrich-Turner or Bonnevie-Ullrich-Turner, is also called gonadal dysgenesis (45XO). It is is a genetic condition that can only affect females in which she does not have the usual pair of two X sex chromosomes. Each person has 46 human chromosomes that contain all of our genes and DNA, or the building blocks of the body. In Turner Syndrome, which encompasses several conditions, cells are missing all or part of an X chromosome. Most commonly, the affected female has only one X chromosome (45XO); others may have two X chromosomes, but one of them is incomplete (Turner mosaicism). Sometimes, a female has some cells with two X chromosomes, but other cells have only one. About half of all individuals with TS have monosomy X in which each cell in the body has only one copy of the X chromosome instead of the usual two.
The gene on the X chromosome that is responsible for most of the features of Turner syndrome is still undetermined. Ultimately, the specific cause of Turner is unknown. However, researchers have been able to identify the gene responsible for short stature and skeletal abnormalities, which is the SHOX gene. The SHOX gene is important for bone development and growth.
Turner is the second most common genetic disorder. It is estimated that the disorder affects 1 in 2,000 females; 1,000 new baby girls are born with the Syndrome annually (one every eight hours). The actual percentage may be higher: there is a wide range of symptoms and not all individuals affected by it experience the same effects; hence, many individuals may go undiagnosed.