Trisomy 13

Trisomy 13

Trisomy 13 or Patau syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 13 in some or all of the body's cells. This condition will make the baby born with physical abnormalities and intellectual disorders.

Under normal conditions, the fetus has 23 pairs of chromosomes , which are genetic carriers inherited from parents. While in trisomy 13, there are more copies of chromosome 13 where there should only be a pair.

Trisomy 13 or Patau's syndrome causes disruption of fetal growth and development. This increases the risk of miscarriage, the fetus dies in the womb , or the baby dies some time after birth. Only 5–10% of babies with trisomy 13 live to be more than 1 year old.

Trisomy 13 causes

Trisomy 13 is caused by a genetic disorder during the process of fertilization, which is the process when a sperm cell unites with an egg to form a future fetus. The disorder causes an extra copy of chromosome 13.

Apart from genetic disorders, an additional copy of chromosome 13 can also occur due to the attachment of chromosome 13 to another chromosome ( translocation trisomy 13 ). Translocation trisomy is a condition passed down from parents to children.

Based on the extra copies formed, trisomy 13 is classified into:

  • Simple trisomy 13, which is when there is an extra 1 copy of chromosome 13 in all cells of the body
  • Mosaic trisomy 13 , which is when there is an extra 1 copy of chromosome 13 in some body cells
  • Partial trisomy 13, which is when there are extra partial copies that are not intact on chromosome 13 in body cells

Simple trisomy 13 causes the most severe symptoms compared to other types of trisomy 13. Patients with simple trisomy 13 are generally shorter in age than patients with mosaic trisomy 13 and partial trisomy 13.

Factors that are thought to increase the risk of developing a genetic disorder that causes trisomy 13 is the age of the mother when she is pregnant. The older the mother is at the time of pregnancy, the higher the risk for the baby to experience genetic disorders, including trisomy 13.

Symptoms of Trisomy 13

Trisomy 13 can cause impaired fetal development. As a result, babies are born with low birth weight and suffer from various health problems.

Generally, babies who suffer from Patau syndrome also experience disorders of the brain structure holoprosencephaly (HPE), which is a condition when the brain is not divided into two parts. This can have an impact on the baby's facial features which are characterized by:

  • Harelip
  • Structural disorder of the eye ( coloboma )
  • One or both eyes are smaller ( microphthalmia )
  • One or both eyeballs are missing (anopthalmia)
  • The distance between the two eyes is too close ( hypotelorism )
  • Developmental disorders of the nasal passages
  • Lower jaw is smaller than normal ( micrognathia )

Apart from the symptoms above, the following conditions can also occur in babies who have trisomy 13:

  • Microcephaly , which is a baby's head size that is smaller than a normal baby's head size
  • Cutis aplasia , which is a condition where some of the scalp is missing or absent
  • Hemangioma , which is a birthmark that is red and prominent
  • Deafness and ear deformities
  • Polydactyly , which is an excess number of fingers or toes
  • Hernia , namely the protrusion of certain organs or body parts
  • Omphalocele , namely the discharge of organs in the baby's abdominal cavity
  • Rocker bottom feet, namely the shape of the soles of the feet are rounded and the heels protrude
  • Cryptorchidism and very small penis size in baby boys
  • The clitoris is large in baby girls

When to see a doctor

Signs and symptoms of trisomy 13 or Patau's syndrome will be immediately visible when the new baby is born. The doctor will immediately provide treatment according to the condition the baby is suffering from.

In addition, pregnant women need to carry out routine checks to the doctor to determine the health condition and development of the fetus. Congenital abnormalities, such as trisomy 13, can usually be identified through pregnancy tests carried out from 10-14 weeks of gestation.

Diagnosis Trisomi 13

Trisomy 13 or Patau syndrome can be detected during pregnancy or after the baby is born. The following is an explanation:

Diagnosis during pregnancy

To check whether there are abnormalities in pregnancy, doctors can do the following methods:

1. Combined test

Chromosomal abnormalities can be seen from the amount of fetal DNA in the mother's blood and the level of fluid found under the skin on the back of the neck of the fetus. This information can be found by carrying out a combined test consisting of a blood test and  ultrasound nuchal translucency (NT) .

The combined test is generally done at an early age of pregnancy, which is around 10-14 weeks.

2. Ultrasonography (USG)

Ultrasound can be done after 17 weeks of gestation. This examination can identify the shape and size of the fetal organs. Generally, babies who suffer from trisomy 13 have abnormalities in body shape and facial features.

3. Tes cytogenetic

If the fetus is suspected of having Patau syndrome, a cytogenetic test will be performed to check the fetal chromosomes. The following are some tests to detect chromosomal abnormalities that doctors can perform:

  • Non-invasive prenatal testing (NIPT), by taking blood samples from pregnant women containing fragments of fetal DNA at 10 weeks' gestation
  • Chorionic villus sampling (CVS), by taking a sample of amniotic fluid at 11–14 weeks of gestation
  • Amniocentesis , by taking samples of amniotic fluid and placental tissue at 15–20 weeks of gestation

Diagnosis when the baby is born

Trisomy 13 is sometimes detected after the baby is born. This can be caused by pregnancy checks which are sometimes not done routinely by pregnant women.

When the baby is born, the doctor will carry out a physical examination and check for signs of trisomy 13. To confirm the diagnosis and severity of the condition, the doctor can carry out supporting examinations, such as X-rays or MRI photos .

Treatment of Trisomy 13

Trisomy 13 cannot be cured. New treatment is limited to reducing the discomfort experienced by the baby, as well as ensuring that the baby gets adequate nutrition.

Most people with Patau syndrome die in the first year of life and rarely reach their teens. Therefore, the doctor will be careful in deciding the right treatment method for the safety of the baby.

Treatment for trisomy 13 can be therapy or surgery, depending on the symptoms and severity of the condition.

Trisomy 13 complications

Babies with trisomy 13 can have many serious health problems. Trisomy 13 complications will usually arise from the time the baby is born. Some of the complications that can occur as a result of suffering from trisomy 13 are:

  • Congenital heart disease
  • Nervous system disorder
  • Heart failure
  • Intellectual disorder
  • Hypertension
  • Pneumonia
  • Kidney disorders
  • Hearing impairment and deafness
  • Visual impairment
  • Growth disorders
  • Difficulty eating
  • Difficulty breathing to stop breathing ( apnea )
  • seizures

Prevention of Trisomy 13

During pregnancy, pregnant women need to undergo routine checks to the doctor . This examination is useful for detecting disturbances or abnormalities in the fetus early on so that treatment can be given immediately.

The following is the recommended pregnancy control schedule:

  • 4th to 28th week: 1 time per month
  • Week 28 to 36: every 2 weeks
  • Week 36 to 40: Once a week

If you have a child with trisomy 13 caused by a trisomy 13 translocation , you and your partner need to undergo genetic counseling and testing . This aims to find out how big the risk of trisomy 13 is in future pregnancies.

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