What are the other Names for this Condition? (Also known as/Synonyms)
- Bartholin-Patau Syndrome
- Chromosome 13 Duplication Syndrome
- Patau Syndrome
What is Trisomy 13 Syndrome? (Definition/Background Information)
- Trisomy 13 Syndrome is a genetic disorder characterized by the presence of an extra 13th chromosome material. The abnormal cells may have entire extra chromosome 13 or may have extra partial 13 chromosomes. Based on this, the syndrome could either be a Complete Trisomy 13 or a Partial Trisomy 13
- Typically, a single pair (or 2 numbers) of chromosome 13 is present; but, in this condition an extra chromosome 13 is observed, making it 3 (hence the term Trisomy 13). This syndrome affects normal growth and development, due to the presence of the extra genetic material
- It affects 1 in 10,000 newborn babies and there is a high mortality rate, with most deaths occurring before the age of 1 year (about 80%)
- There is no cure for the condition and the treatment measures followed are mostly symptomatic. The prognosis for Trisomy 13 Syndrome is poor
Who gets Trisomy 13 Syndrome? (Age and Sex Distribution)
- Trisomy 13 Syndrome is a congenital condition. It affects the newborn child
- It is a random genetic occurrence; there is no gender predilection, and it is not an inherited condition
- However, Trisomy 13 that is caused by a translocation (when a genetic material of one particular chromosome is attached to another different chromosome during cell division), could be inherited
What are the Risk Factors for Trisomy 13 Syndrome? (Predisposing Factors)
Trisomy 13 Syndrome risk factors include:
- There seems to be a link between the maternal age (during pregnancy) and the onset of this disorder, with an increasing maternal age, increasing the risk
- Individuals, who are unaffected by an anomalous rearrangement of the genetic material (termed as a balanced translocation), may pass on the disorder to their offspring. There is an elevated risk under such circumstances
It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.
Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.
What are the Causes of Trisomy 13 Syndrome? (Etiology)
- Trisomy 13 Syndrome takes place due to a chromosomal anomaly, when an additional copy of the genetic material found on the 13th chromosome is carried forward during fertilization. If all of the genetic material is copied and taken forward, then it is termed as a Complete Trisomy 13, else it is termed Partial Trisomy 13
- The extra material causes 47 chromosomes (23 pairs and a single extra 13th chromosome) to be present in the developing fetus, leading to serious medical complications. Under normal circumstances, a healthy egg and sperm contributes 23 (haploid) chromosomes each, totaling 46 chromosomes to the developing fetus
- It is researched that the cause may lie either in the egg cell or in the sperm cell (maybe a cell division error), which after fertilization creates three copies (trisomy) of the 13th chromosome, rather than 2 normal copies
- In some cases, all body cells are not found to have this extra chromosome, but only a small proportion of cells are found to have them. This causes a mixed cell population with different chromosome numbers (quantity) known as ‘Mosaic Patau Syndrome’. In such cases, the severity of the signs and symptoms are less than those observed with a Complete T13 Syndrome. Despite this, a Partial Mosaic Patau Syndrome could still be fatal
What are the Signs and Symptoms of Trisomy 13 Syndrome?
Most pregnancies are terminated and most babies die, before or within one year of birth; Trisomy 13 Syndrome has a high fatality rate. However, of the surviving few, the signs and symptoms are mainly related to growth deficiencies and delayed or imbalanced development. All the vital organs, such as the brain, nervous system, bones and muscles, heart, etc. can be affected.
- In newborn babies, the following signs and symptoms of T13 Syndrome are generally observed:
- Clenched fists
- Extra digits on hands and legs
- Severe mental deficiencies
- Small head, small eyes and jaw
- Cleft lip and palate
- Decreased muscle function
- Skeletal, urogenital abnormalities
- A developing fetus in the womb may show:
- Heart defects
- Differently arranged internal organs
- Brain structure abnormalities
How is Trisomy 13 Syndrome Diagnosed?
Chromosomal studies (karyotyping using a sample of the blood or amniotic fluid) for Trisomy 13 Syndrome can confirm the type and severity of the disorder (such as complete, partial or mosaic). Other exams and tests that are performed may include:
- Ultrasound scans or x-ray images to study internal organ arrangement
- MRI or CT scans of the brain to check for holoprosencephaly (lack of growth of the embryonic forebrain)
- Studies to detect congenital heart defects
- Other physical findings are correlated with the above
Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.
What are the possible Complications of Trisomy 13 Syndrome?
Complications that develop due to Trisomy 13 Syndrome, depends on the severity of the syndrome. Partial Trisomy 13 has less severe signs and syndrome compared to complete Trisomy 13. They also depend on the kind of specific defects and abnormalities that are observed. Invariably, all babies are known to have:
- Feeding problems
- Shortness of breath
- Heart and vision defects
How is Trisomy 13 Syndrome Treated?
An individualized treatment (a case-by-case approach) is planned and provided for Trisomy 13 Syndrome, based on the specific conditions/complications that develop.
- However, both partial T13 Syndrome and complete T13 Syndrome have no known cures
- In children, who survive the first few years, some of the physical defects may be corrected using surgical procedures (like for cardiac and other abnormalities)
- In order to improve motor skills and mental disabilities, special therapeutic treatment (by speech, physical, and occupational therapists) and supportive care are to be provided
How can Trisomy 13 Syndrome be Prevented?
- Currently, there are no specific methods or guidelines to prevent Trisomy 13 Syndrome genetic condition
- Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
- If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
- Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders
What is the Prognosis of Trisomy 13 Syndrome? (Outcomes/Resolutions)
- Trisomy 13 Syndrome (either partial or complete) is a fatal genetic disorder
- Most children, who survive the initial few years, are severely affected by multiple congenital defects and developmental deformities. However, with constant care and support by families and medical aids, some affected individuals are able to manage their lives
Additional and Relevant Useful Information for Trisomy 13 Syndrome:
There are voluntary organizations and support groups that provide help and understanding to the families and parents of the Trisomy affected.