●Trisomy 13 (Patau Syndrome)

Q: What causes Trisomy 13?

The causes are classified into three types. Standard type (approx. 80%) is caused by the failure of chromosomes to separate correctly during the formation of reproductive cells. Translocation type (approx. 15%) occurs when a part of chromosome 13 attaches to another chromosome, which can be inherited from a parent. Mosaic type (approx. 5%) is a state where both normal and abnormal cells coexist in the body.

Q: Can Trisomy 13 be tested during pregnancy?

Yes, Non-Invasive Prenatal Testing (NIPT) allows for a non-invasive assessment of the risk of fetal Trisomy 13 during pregnancy. NIPT analyzes cell-free fetal DNA fragments in the maternal blood and can be performed from 10 weeks of gestation.

Trisomy 13 is a congenital disorder caused by a chromosomal abnormality, also known as "Patau syndrome". It was named Patau syndrome because it was discovered and reported by Klaus Patau and others.

Trisomy 13 (Patau syndrome) is a chromosomal abnormality that occurs in approximately 1 in 10,000 to 20,000 live births, and is more common in females (male-to-female ratio of 1:2). ^*1

\ Discover the risk of fetal Patau syndrome /

For details on
NIPT, click here

Causes

Patau syndrome (Trisomy 13) occurs when there are three copies of chromosome 13 instead of the usual two.
This chromosomal abnormality occurs due to several causes as follows. *2

Standard Type (Trisomy 13)
During the formation of parental reproductive cells (egg or sperm), chromosomes fail to separate correctly, resulting in an extra copy of chromosome 13 being included in the child's cells.
Consequently, there are three copies of chromosome 13.
Approximately 80% of Patau syndrome (Trisomy 13) cases are said to be caused by this chromosomal nondisjunction.

Translocation Type
This occurs when a portion of chromosome 13 becomes attached (translocated) to another chromosome.
If either parent carries a translocated chromosome, Trisomy 13 can be inherited.
Approximately 15% of Patau syndrome (Trisomy 13) cases are of this translocation type.

Mosaic Type
This case is observed in about 5% of Patau syndrome patients, where a mixture of cells with chromosomal abnormalities and cells with a normal number of chromosomes exists in the body. Depending on the proportion of cells with the abnormality, symptoms of Patau syndrome may be milder.

Since Patau syndrome is caused by a chromosomal change occurring during the formation of parental reproductive cells, it cannot be prevented. While it is known that the risk increases with maternal age, it can also occur in children born to younger mothers.

Symptoms

Patau syndrome (Trisomy 13) is characterized by several distinctive symptoms, but they vary from individual to individual. *3

Physical Features
• Microcephaly
• Eye abnormalities
• Cleft lip and/or palate
• Limb abnormalities

Cognition and Development
• Severe intellectual disability
• Developmental delay

Health Issues
• Congenital heart disease
• Respiratory diseases
• Kidney and gastrointestinal disorders

Pregnancies in which Patau syndrome is identified in the early stages carry a high probability of miscarriage or stillbirth.
Statistics show a survival rate of approximately 50% at one month and 10% at one year after birth, though there are cases of individuals surviving into adulthood.

Treatment

While there is currently no fundamental cure for Patau syndrome, medical care and developmental support tailored to various symptoms are provided.
Recently, it has been reported that medical interventions such as neonatal intensive care and heart surgery have led to an increasing number of cases with improved survival prognosis.

Neonatal Intensive Care
Monitoring the newborn's heart rate, respiratory rate, blood oxygen levels, and blood pressure on a 24-hour basis, and administering various treatments such as mechanical ventilation, oral medications, and intravenous drips as needed.

It is crucial to consider the medical care, developmental support, and family assistance needed for children with Patau syndrome. *4

References

Reference 1: Cleveland Clinic Reference 2: Mount Sinai Health System Reference 3: Patau Syndrome.Reference 4: National Organization for Rare Disorders

Frequently Asked Questions

Q.What is Trisomy 13 (Patau syndrome)?

Trisomy 13 (Patau syndrome) is a congenital chromosomal abnormality caused by having three copies of chromosome 13 instead of the usual two. It was first reported by Klaus Patau et al. in 1960. The incidence is approximately 1 in 10,000 to 20,000 births, with a higher prevalence in females (male-to-female ratio of 1:2)(1).

Q.What causes Trisomy 13?

The causes are classified into three types. Standard type (approx. 80%) is caused by the failure of chromosomes to separate correctly during the formation of reproductive cells. Translocation type (approx. 15%) occurs when a part of chromosome 13 attaches to another chromosome, which can be inherited from a parent. Mosaic type (approx. 5%) is a state where both normal and abnormal cells coexist in the body(2).

Q.What are the main symptoms of Trisomy 13?

Physical features include microcephaly, eye abnormalities, cleft lip and/or palate, and limb abnormalities. It is accompanied by severe intellectual disability and developmental delay, as well as complications such as congenital heart disease, respiratory diseases, and kidney or gastrointestinal disorders. The survival rate after birth is approximately 50% at one month and 10% at one year, although some individuals survive into adulthood(3).

Q.Can Trisomy 13 be tested during pregnancy?

Yes, Non-Invasive Prenatal Testing (NIPT) allows for a non-invasive assessment of the risk of fetal Trisomy 13 during pregnancy. NIPT analyzes cell-free fetal DNA fragments in the maternal blood and can be performed from 10 weeks of gestation(4).

Q.Is there a treatment for Trisomy 13?

There is currently no fundamental cure. However, symptomatic treatments such as 24-hour monitoring in the neonatal intensive care unit (NICU), mechanical ventilation, and cardiac surgery are increasingly improving the survival prognosis. A comprehensive approach combining medical care, developmental support, and family assistance is essential(5).