What is Mosaic Turner Syndrome?
Chromosomal arrangement distinguishes female embryo to male embryo. In the female, sex chromosome arrangement is demonstrated as XX, whereas XY arrangement is a male. Mosaic Turner syndrome is a sex chromosomal disorder occur in females.
In Mosaic Turner Syndrome, missing of an X chromosome at the primary stages of embryonic development causes the certain cellular structure of the body receive a single X chromosome. This abnormal phenomenon is termed as mosaicism. The chromosomal arrangement of Mosaic Turner Syndrome within the body is 45, as one X chromosome lost, instead of 46, with XX sex chromosomal arrangement1,2.
Female child born with Mosaic Turner Syndrome is rare and that about 1 in 2,500 girl child birth. However, the frequency of the onset of disease during pregnancy is quite frequent, but mostly embryo unable to survive till full term due to miscarriages and stillbirths. Therefore the actual birth with Mosaic Turner Syndrome is less3.
Usually, a certain number of cells affected and that usually not significant to produce moderate to severe symptoms associated with Turner Syndrome. Therefore, relatively mild symptoms are associated with Mosaic Turner Syndrome. For example, females with Turner Syndrome have completely absent menstrual cycle, but females with mosaic Turner syndrome have menstrual cycles till their late 20s1.
In Mosaic Turner Syndrome, instead of two chromosomes a girl born with one chromosome in certain cells. During an embryo development, sperm and egg both are contributed 23 chromosomes and embryo with 23 pairs of chromosomes.
But in the case of Mosaic Turner Syndrome, either egg or sperm contains 22 chromosomes and join with 23 chromosomes and resultant of this leads to the development of embryo with 45 chromosomes. In Mosaic Turner Syndrome, some cells have only one copy of a chromosome, instead of two copy and this whole abnormal arrangement is termed as monosomy. Usually, this syndrome has inheriting influence.
In Mosaic Turner Syndrome, at the early developmental stage of an embryo, a faulty cell division may occur and resultant of this causes some cells lost pair of X chromosome, while other cells have two X chromosome copies. In some cases, alter cellular arrangement may develop, in which one cell has both X chromosome copies, but the next cell does not have both copies of X chromosome2,3.
Pregnancy at above 35 years of female age may have a higher risk of chromosomal disorder, therefore, performing chromosome testing during pregnancy can assist to detect chromosomal disorder.
- Prenatal chromosome test can be conducted with a number of different ways. The bust usual process involves a screening test and a diagnostic test. The risk of probable health issues can be estimated through screening tests. A screening test is non-invasive and does not perform by taking a sample from the developing embryo, therefore it is a safe to process. Ultrasound along with another testing at first and second trimester is considered as a screening test.
- In the case of any abnormality findings diagnostic tests are performed, in which directly embryo is tested. During this process, a small risk of losing the baby should be considered before performing the test. Different investigative techniques like ultrasounds, amniocentesis and chorionic villus sampling are involved.
- A blood test known as Karotype performs to detect additional or absent chromosomes, chromosomal breaks or chromosomal rearrangements. Karotype blood test can be conducted by taking a small portion of amniotic fluid as a sample at the time of embryo present in the mother’s uterus, or blood sample collected from a child/baby. Incomplete or loss of one X chromosomes confirmed the developing embryo or child has Turner Syndrome.
The above-mentioned diagnosis process needs to discuss with parents thoroughly and depending upon the mutual decision testing should proceed. Diagnostic testing is not a compulsory process, but an optional method.
Pre-implantation genetic diagnosis (PGD) is a screening option to detect chromosome conditions within a developing embryo by using in vitro fertilization (IVF). This is an another option, which clinician can discuss with a parent with the chromosomal disorder with possible risk- benefits of this option2,3,4.
Mosaic Turner Syndrome is a non-curable condition. However, in Mosaic Turner Syndrome symptoms are mild, but the management of the patient depends upon the symptomatic approach to the patient.
- The first and foremost important management for a female with Mosaic Turner Syndrome should maintain follow-up process. During the follow-up, routine monitoring of the patient is very important to early preventive measures. Blood pressure measurement and thyroid gland functioning are important for these type of patients and any abnormality should medically treat.
- Estrogen and progesterone replacement may require continuing sexual development and continuation of the menstrual cycle. Estrogen hormonal replacement therapy usually needs to start after puberty with a low dose and gradually dose needs to increase with increasing of age. Progesterone may require continuing the menstrual cycle at late of 20 years of age. This hormonal replacement therapy has different formulations, including pills, patches, and injections. The proper estrogen level also prevents bone degeneration.
- Female with Mosaic Turner Syndrome has a risk of short physique, this problem can be solved by treating a patient with growth hormone at her early childhood.
- Females with Mosaic Turner Syndrome may have conception problem. Therefore, the assistance of in vitro fertilization can give them an opportunity to become a mother. However, extra care is required during gestation to avoid complications 4.
- Mosaic Turner Syndrome; Retrieve from http://genetics.emedtv.com/mosaic-turner-syndrome/mosaic-turner-syndrome.html
- Fact Sheet: Turner Syndrome; Retrieve from http://www.genetics.edu.au/Publications-and-Resources/Genetics-Fact-Sheets/FactSheet40TurnerSyndrome.pdf%20
- Turner Syndrome; Genetic Home References; Retrieve from https://ghr.nlm.nih.gov/condition/turner-syndrome?_u=b897-33f7&utm_expid=.qfbuu21fTGm4jYz6mrmJMw.1&utm_referrer=https%3A%2F%2Fwww.google.co.in%2F
- Christian Nordqvist (2014); What is Turner syndrome? What causes Turner syndrome? Retrieve from http://www.medicalnewstoday.com/articles/176083.php