What is trisomy 13 (Patau syndrome)?

Trisomy 13 is a genetic disorder in which a child has an extra 13th chromosome. People with this trisomy have three copies of chromosome 13, when they should have only two copies. This happens when cells divide abnormally during reproduction, creating extra genetic material on chromosome 13.

The extra chromosome can come from the egg or sperm, but doctors believe that mothers over 35 are more likely to have a baby with any chromosomal abnormality. The extra 13th chromosome brings severe mental and physical problems. Unfortunately, most babies with this disorder do not live more than a month or a year. Of course, some of them continue to live for years.

In fact, this difference is due to the existence of two different types of trisomy 13. Sometimes trisomy babies have three copies of chromosome number 13 in all their cells. In some cases, this increase in chromosomes is only in some cells. Symptoms appear depending on the number of cells that have an extra chromosome.

Signs and symptoms of trisomy 13 or Patau syndrome

Heart abnormalities at birth (congenital).
A physical growth disorder with many cases involving the spinal cord.
Severe problems with cognitive function

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Underdeveloped internal organs.

Physical symptoms

Cleft lip (cleft palate).
Difficulty gaining weight.
Extra fingers (polydactyly).
Ears are formed at the bottom of the head.
Developmental disorders in the arms and legs.
Low muscle power (hypotonia).
Small head and lower jaw.
Eyes very small, close together or underdeveloped.

Internal organ symptoms

Gastrointestinal (GI) problems that make eating difficult.
heart failure
Hearing problems.
underdeveloped lungs
vision problems

Causes of trisomy 13 or Patau syndrome

A third chromosome 13 attached to a chromosome pair causes trisomy 13. A person with trisomy 13 has 47 total chromosomes. Normally there are 46 chromosomes in the body. Chromosomes carry DNA in cells, which act as instructions to tell the body how to form and function. Cells are initially formed in the reproductive organs by division of a cell that is a combination of sperm and egg and fertilized. Newer cells divide and copy themselves with half the amount of DNA of the original cell. During this process of cell division, a trisomy (when a third chromosome joins a pair) can occur randomly as the cell copies its DNA again. Whenever there is an error in copying, the symptoms of trisomy 13 occur because the cells do not have the instructions to form and function correctly. There are three possible ways for trisomy to form on chromosome 13, depending on how the chromosomes fold.

Diagnosis of trisomy 13 or Patau syndrome

During the first trimester, your doctor may offer genetic testing in addition to prenatal ultrasounds, with tests as early as 11 to 14 weeks to check for genetic changes, such as: a third chromosome attached to a pair. Confirmation of the diagnosis occurs after the baby is born, when the doctor can examine the baby for symptoms and offer additional tests if necessary.

Tests needed to diagnose trisomy 13 or Patau syndrome

The doctor offers screening tests during pregnancy to test a blood sample in addition to an ultrasound. During the ultrasound, the doctor will look for signs of trisomy, such as: extra amniotic fluid. The most common diagnostic test for trisomy 13 is the karyotype test.

Treatment of trisomy 13 or Patau syndrome

Educational support
Genetic counseling
Medications to relieve symptoms
Speech, behavior and physiotherapy
Surgery to correct any physical deformity