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Causes of Turner Syndrome



Normally, people are born with two sex chromosomes. Males inherit the X chromosome from the mother and the Y chromosome from the father while females inherit one X chromosome from the mother and one from the father. In the case of Turner syndrome, one of the X chromosomes in the female is absent or altered. The causes of turner syndrome are related to the type of alterations which occur in the X chromosome. These include the following:

• Monosomy: This is a condition in which all the body cells have a single X chromosome. This abnormality may occur due to a defect in the egg or sperm.
• Mosaicism: In this condition, some cells have just a single copy of the X chromosome or one complete copy and one incomplete copy. This occurs due to errors during the early stages of cell division in the fetus.
• Y Chromosome Material: In a few girls with Turner syndrome, some of the body cells have one copy of the X chromosome while the other cells have Y chromosome material along with a copy of the X chromosome. Female biological development occurs in such cases, but there is a risk of developing gonadoblastoma, a form of cancer.

Chromosomal abnormalities can lead to various complications during the development of the fetus. There may be developmental problems even after birth and girls with Turner syndrome may have learning disabilities, ovarian failure and short stature.

The absence or alteration of the X chromosome may be attributed to a defect in the egg or sperm. In some cases these errors may occur during the early stages of fetal development. Turner syndrome can lead to the following complications:

• Many females with Turner syndrome have heart defects which can increase the risk of serious complications.
• Women with Turner syndrome are at a greater risk for developing high blood pressure and diabetes. Both these conditions can increase the risk of cardiovascular disease.
• Hearing loss may occur due to problems in nerve function. Defects in the shape of the skull may also lead to ear infections which can gradually result in hearing loss.

Some girls with Turner syndrome may have abnormalities in the kidneys which do not lead to medical complications, but can increase the risk of urinary tract infections and hypertension.

• Women with Turner syndrome may be susceptible to disorders of the immune system.
• Abnormalities in tooth development may increase the risk of tooth loss.
• Poor muscle control over eye movements may lead to vision problems.
• Poor development of the bones may lead to scoliosis or brittle bones.
• Girls with Turner syndrome may experience anxiety, depression and low self esteem.