Patau syndrome: A picture of trisomy 13

During conception, genetic material is donated from mother and father. During this process, 46 pairs of chromosomes line up along an embryo’s strands of DNA and create the blueprint for everything from appearance to growth and development. 23 chromosomes come from the mother and 23 from the father. In most cases, this process goes smoothly. But occasionally, problems transferring this information cause additional genetic material to develop—adding a third chromosome to a pair of two. This condition is known as a trisomy.

Symptoms of a trisomy will vary depending on what chromosome is affected and can range from mild to severe.  Trisomy 13 affects the 13th chromosome and brings with it significant health impacts. Known as Patau syndrome, trisomy 13 is a rare chromosomal disorder affecting 1 out of every 8,000-12,000 live births.

trisomy 13

What causes Patau syndrome?

Despite years of continuing research, the medical community still doesn’t know what causes Patau syndrome or how to prevent it. We do know that women who are 35 years old or older at their due date have a higher risk of having a baby with a trisomy and the risk climbs with age. There also doesn’t seem to be any link between race or ethnicity and Patau syndrome.

What are the symptoms of Patau syndrome?

Patau syndrome affects nearly every part of the body with a special impact on the central nervous system. Stillbirth and fetal demise are common, but babies who are born alive may also have:

  • Low APGAR scores at birth
  • Cleft lip or cleft palate (openings in the upper portion of the mouth and lip)
  • Extra fingers and toes
  • An abnormally small head
  • Hernias
  • Neural tube defects
  • Omphalocele (intestines or abdominal organs are on the outside of the body)

Babies born with Patau syndrome have multiple birth defects and often don’t survive the first few months of life.

Can Patau syndrome be detected early?

Yes. Your doctor will offer prenatal genetic testing during your first and second trimester of pregnancy. Not all tests can be done in the second trimester, so if you want testing, it’s best to do it as early as possible. Prenatal testing is completely optional. Not every parent wants to know and some others do—the decision is yours.

trisomy 13 testing

Patau syndrome can be identified through non-invasive prenatal testing that uses a sample of maternal blood. This blood sample carries DNA from the baby that can be tested for genetic disorders.  This test can be completed as early as 10 weeks gestation. Other blood tests and ultrasound technology may also be used.

If the test is positive, your doctor will want to do more invasive testing to gather cells or fluid from around the fetus to verify the results. This means using a needle to gather the sample through amniocentesis or chorionic villus sampling (CVS). You should talk to your doctor about what confirmatory tests he or she recommends.

Other resources for Patau syndrome

Men and women who have a family history of genetic disorders should consider seeing a genetic counselor prior to conception. Expectant couples can also be referred for counseling if a genetic disorder is identified in a developing fetus.

The counselor will be able to offer resources on screening tests, details about the symptoms of a disorder, emotional support, and additional community and medical resources.