Understanding Patau Syndrome

We all know about down syndrome but it isn't the only thing you need to watch for when you are pregnant at 30 or older - learn about Patau Syndrome

My husband and I are very happy with the size of our family, but sometimes we can’t help but get baby fever.  Although we have no intentions of making our littlest become a big brother, it could happen.  It would be a blessing and we would be grateful for the addition to our family, but baby development is often a big concern when you are 30 years or older so that is something we need to be aware of.

The correlations between advanced maternal age and the incidence of Down syndrome is commonly discussed, but there are other syndromes associated with advanced maternal age that are not as widely known. Trisomy disorders are the most common chromosomal disorders of babies born to mothers of 35 years and older.

Each individual has 23 pairs of chromosomes – 22 pairs of autosomal chromosomes and 1 pair of sex chromosomes. When fragments of chromosomes are deleted, duplicated, inverted, or translocated, chromosomal abnormalities occur. A trisomy disorder is a duplication abnormality characterized by three copies of a chromosome, instead of the typical pair. Patau syndrome manifests as a trisomy of chromosome 13.


How Common is Patau Syndrome?

Each year, 1 in 16,000 babies are affected by Patau syndrome. The risk of a baby developing Patau syndrome is significantly increased at the maternal age of 35 and increases each year onward.


Signs and Symptoms of Patau Syndrome

Characteristics of Patau syndrome include:

  • Cleft palate or cleft lip
  • Clenched hands
  • Extra fingers and toes
  • Eyes that are set closer together
  • Ears that are set low
  • Small head


How Does Patau Syndrome Occur?

According to genetics.edu.au, the chromosomal problem in trisomy 13 is typically due to an egg cell containing an additional copy of chromosome 13. When the egg is fertilized by a sperm cell, the result is 47 chromosome rather than the typical 46.

Trisomy 13 can manifest in one of the following ways:

  1. a)  Non-disjunction – When all of the individual’s cells have 3 chromosome 13s. This is referred to as Trisomy 13.
  2. b)  Mosaicism – When only some of the individual’s cells have 3 chromosome 13s. This is referred to Trisomy 13 mosaicism.
  3. c)  Translocation – When cells contain part of an extra chromosome 13. This is referred to as a partial trisomy.


Diagnosing Patau Syndrome

Prenatal Screening

Prenatal ultrasounds may show evidence of extreme physical abnormalities, such as limb and organ deformations, which may indicate a likelihood of Patau syndrome. Prenatal trisomy tests may also be used to assess the risk that your child may have a chromosomal abnormality. Non-invasive prenatal DNA testing options that require only a blood draw from the biological mother are also available.


Diagnostic testing

If screening tests show that there is a high probability your child has a chromosomal abnormality, more than likely your physician may present you with diagnostic testing options. Some of your options may include invasive procedures, such as chorionic villus sampling (CVS) or amniocentesis.

For couples who have a family history of genetic disease, or a previous pregnancy with a genetic disease, it is a good idea to speak with your healthcare provider or a genetic counselor to better understand if prenatal tests should be considered.


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