Triple X chromosome syndrome | What we need to know

X chromosome trisomy (or triple X chromosome syndrome, or 47XXX) is a genetic disorder. It belongs to the group of disorders with aneuploidy - i.e. changes in the number of chromosomes. The human chromosomal set consists of 23 pairs, or 46 chromosomes, half of which he receives from his mother and half from his father. The twenty-third chromosome pair is known as the sex chromosomes. Female sex chromosomes are represented by XX, and male sex chromosomes are represented by XY chromosome. X chromosome trisomy develops when a female fetus receives not one, but two X chromosomes from the mother's gamete (egg).

XXX syndrome is quite rare, with an average of 1000 case per 1 live births.

Mechanism

Triple X syndrome is a genetic disorder characterized by the presence of 1 extra sex X chromosome in females. As a rule, this disorder occurs in the form of a new mutation during the violation of the processes of replication (doubling) and division of chromosomes, during the subsequent process of gamete formation or fertilization, and is random in nature.

Women over the age of 35 are much more likely to have a daughter with chromosomal aneuploidy. There may also be triple X chromosome mosaicism, where cells with a triple X chromosome and a normal set of chromosomes coexist. The reason for this is the division of embryonic cells.

Symptoms

Clinical manifestations of girls with triple X syndrome are very diverse. In some individuals, there are no symptoms, or they are so minimal that they are practically unnoticeable. Some girls may have certain characteristics associated with triple X syndrome. The main characteristic that is noticeable in this syndrome is the height of the girls - they are much taller than their parents or their population average. Other physical characteristics may be present to a greater or lesser degree, such as:

• Large gap between the eyes (hypertelorism)
• Vertical fold of skin near the inner corner of the eye (epicanthic fold)
• Curved or curved short fingers
• Decreased muscle tone

In some cases, problems such as:

• Premature aging or functional failure of the ovaries, which may be associated with infertility
• Dysfunction of the urogenital system or various anomalies (kidney, ovary)
• Hearts
• Structural changes and dysfunction of the heart
• Autoimmune diseases, eg: thyroid gland

Some girls have developmental delays or psychological and cognitive problems:

• attention deficit
• Mood disorders
• Delay in physical development - associated with muscle hypotonus
• Disruption of learning processes
• Social problems – difficulties in social integration and communication, low self-esteem.
• Moderate cognitive-intellectual disorders: IQ is on average within the norm, or may be only 10-15 units below the norm.

Diagnosis

Triple x syndrome is diagnosed mainly through prenatal diagnostics. In order to confirm the diagnostics, it is necessary to carry out genetic research, after Bashvi's birth - by the method of karyotyping. Suspicion of the disease is sometimes made through developmental delay or characteristic physical features of the female infant or fetus.

If the developmental delay and characteristic clinical-anatomical changes are not detected, such girls may not be diagnosed. In some cases, the diagnostics is discovered only when researching the causes of a woman's infertility or early menopause.

Treatment and management

There is no treatment for triple X syndrome. Treatment issues depend on the detected disorders. Depending on the need, a nephrologist, cardiologist, neurologist, neuropsychologist, reproductive specialist are involved in the treatment process.

Laboratory "Synevo" offers non-invasive prenatal diagnostics:

The time for issuing research results is not absolute, it can change taking into account various factors

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Source:

https://my.clevelandclinic.org/health/diseases/17892-triple-x-syndrome

n.manjaparashvili@synevo.ge