Mechanism of Turner syndrome

The article was professionally consulted by Dr. Nguyen Anh Tu - Doctor of Obstetric Ultrasound - Prenatal Diagnosis - Obstetrics Department - Vinmec Hai Phong International General Hospital.

Turner syndrome is the most common chromosomal disorder in females, occurring due to part or all of the X chromosome in the genome. The mechanism causing Turner syndrome is of interest to many scientists, to clarify to effectively prevent this syndrome.

According to research to date, Turner syndrome is the most common sex chromosome disorder in women, causing many developmental disorders both mentally and physically of sufferers.
Turner syndrome and pediatrics are closely related. Normally, more than 90% of fetuses with Turner syndrome will have a spontaneous abortion, but still about 1 in 4,000 girls are born with this syndrome.

Turner syndrome (HC Turner) was first described in detail in 1938 by physician Henry Turner. The mechanism of Turner syndrome was found to be due to partial or complete loss of an X chromosome in the human genome.
In Turner syndrome, due to the complete loss of 1 X chromosome, there is only one X sex chromosome left, this is the most common cause, accounting for about 50%. This case HC Turner is also known as monosomy X, denoted by 45,X or 45,X0.
About one-third of women with Turner syndrome have both X chromosomes, but one is missing a segment.
There are also many cases of patients with Turner syndrome having mosaicism. In their body, there are 2 cell lines that exist in parallel, 1 normal cell line 46,XX and 1 abnormal cell line 45,X. These mosaic cases are more fortunate, often causing milder disorders than Turner syndrome due to the abnormality of partial or complete absence of a true X chromosome.
Sometimes there are also cases of mosaic Turner syndrome with the existence of a cell line containing a part of the Y chromosome that determines the male sex. However, the Y chromosome part is not much, so the male sex phenotype is not generated for the patient. These women have an increased risk of ovarian tumors.
Recently, scientists have identified the SHOX gene located at the short end of the X chromosome, which is mainly a consequence of the loss of a SHOX gene, causing dwarfism.
HC Turner is not curable, but can be diagnosed early in pregnancy to avoid having a baby with Turner.

This is the most common feature of HC Turner, caused by the disappearance of the SHOX growth gene. This process of growth retardation can occur from birth, but the signs become more obvious by the time the child is 3 years old, and as they get older, they become more and more obvious.
If the patient does not have hormone replacement, the patient will continue to grow slowly without the possibility of the growth spurt during puberty. Through many surveys, women with Turner syndrome are usually about 20cm shorter than the average person.

Over 90% of women with Turner syndrome will have premature ovarian failure, which is also the main cause of the majority of women without breasts.
The ovaries are the only place in the body that has the function of producing eggs and female sex hormones to develop the characteristics of the female body such as: physique, breasts, menstruation, female skeletal system.
On average, only about one-third of people with Turner will show signs of breast development, but most do not complete puberty. In particular, less than 1% of patients can get pregnant naturally.

Currently, there are many diagnostic methods to help early detection of Turner syndrome as well as many other syndromes caused by chromosomal abnormalities.
Some traditional diagnostic testing methods such as chromosomal testing performed on amniotic fluid cells have a high detection rate, but still have complications, affecting the fetus. Currently, there is a modern non-invasive prenatal screening method NIPT, which helps to test fetal DNA in maternal blood safely, early detection from the 10th week of pregnancy, high accurate diagnosis rate should be trusted.

NIPT testing is being applied at Vinmec International General Hospital, the leading prestigious hospital in the country thanks to a team of experienced experts who are professionally trained in the country and in countries with scientific background. leading developers in the world such as Germany, Great Britain, France; with a system of modern machinery for fast, accurate and safe results.