Which are the causes of Turner Syndrome?

Turner Syndrome is a genetic disorder that affects females and is characterized by the absence or partial absence of one of the two X chromosomes. It is named after Dr. Henry Turner, who first described the condition in 1938. Turner Syndrome occurs in approximately 1 in every 2,500 live female births.

The causes of Turner Syndrome can be attributed to various genetic abnormalities. The most common cause is a random error in the formation of the egg or sperm cells, leading to the absence of an X chromosome in the resulting embryo. This error occurs during the early stages of fetal development and is not typically inherited from the parents.

Monosomy X, also known as 45,X, is the most common chromosomal abnormality in Turner Syndrome, accounting for about 50% of cases. In these individuals, one of the sex chromosomes is completely missing. Instead of the usual XX or XY, affected individuals have only one X chromosome. The loss of genetic material from the missing chromosome leads to the characteristic features and health issues associated with Turner Syndrome.

Mosaicism is another cause of Turner Syndrome, accounting for approximately 30% of cases. Mosaic Turner Syndrome occurs when some cells in the body have the typical 46,XX karyotype (two X chromosomes), while other cells have the 45,X karyotype (one X chromosome). The presence of both cell lines can result in a wide range of symptoms and varying severity of the condition.

Rarely, structural abnormalities of the X chromosome can cause Turner Syndrome. These abnormalities may include deletions, duplications, or rearrangements of genetic material within the X chromosome. These structural abnormalities can disrupt the normal functioning of genes and lead to the development of Turner Syndrome.

Advanced maternal age is also considered a risk factor for Turner Syndrome. Studies have shown that the incidence of Turner Syndrome increases with increasing maternal age, particularly in women over the age of 35. However, it is important to note that the majority of pregnancies in older women still result in typical chromosomal configurations.

Environmental factors do not play a significant role in the development of Turner Syndrome. It is primarily a genetic condition that occurs randomly and is not influenced by lifestyle, diet, or exposure to toxins.

The consequences of Turner Syndrome can vary widely among affected individuals. Some common features include short stature, webbed neck, low hairline at the back of the neck, and a broad chest with widely spaced nipples. Other physical characteristics may include lymphedema (swelling of the hands and feet), skeletal abnormalities, and heart defects. Additionally, individuals with Turner Syndrome often experience reproductive difficulties, such as infertility and early ovarian failure.

Early diagnosis and appropriate medical management are crucial for individuals with Turner Syndrome. Treatment may involve growth hormone therapy to improve height, hormone replacement therapy to induce puberty and maintain secondary sexual characteristics, and regular monitoring of cardiac and renal function. Psychological support and educational interventions are also important to address the emotional and learning challenges that individuals with Turner Syndrome may face.

In conclusion, Turner Syndrome is a genetic disorder caused by the absence or partial absence of one X chromosome. The most common causes include monosomy X and mosaicism, while structural abnormalities and advanced maternal age can also contribute. It is important to raise awareness about Turner Syndrome, promote early diagnosis, and provide appropriate medical care to improve the quality of life for individuals with this condition.