Fast Facts about Trisomy 13

Fast Facts about Trisomy 13

Trisomy 13 (also called Patau Syndrome) occurs in up to 1 out of 5,000 newborns (Smith’s Recognizable Patterns of Human Malformation, Saunders 1988).

The 13th chromosome contains blueprints that direct a baby’s development in the early weeks following conception. When a child has an extra 13th chromosome (three copies, instead of two), as is the case in trisomy 13, the genetic messages are confused and contradictory. This results in multiple significant defects in major organ systems.

The brain is often the most severely affected. Most children with trisomy 13 also have some kind of heart defect. It’s not unusual for these children to be born blind, deaf, and with no sense of smell. Children with trisomy 13 may also have abnormalities in the shape of their lips, eyes, ears, fingers, toes, and bones.

Trisomy 13 was first described in 1657, but four hundred fifty years of medical knowledge have not improved the outlook for children born with this syndrome.

Most babies who are conceived with trisomy 13 die early in gestation. Of the babies who live to be born, about 44 % die within the first month and 69% die by six months. Only 18 percent reach their first birthdays — and these children tend to have severe mental defects and seizures (Smith’s Recognizable Patterns of Human Malformation, Saunders 1988).

A blood test, called the AFP (alphafetoprotein) or triple screen, may help a pregnant woman find out her baby’s risk of several diseases, including Trisomy 21 (Down Syndrome) and Trisomy 13, though it can not give a definite answer.

Trisomy 13 is often detectable on ultrasound as early as 10 weeks. Chorionic villous sampling can detect trisomy 13 by 12 weeks. Amniocentesis, usually performed after 16 weeks gestation, can give a definite answer if any question still remains.

Often trisomy 13 is associated with older mothers. Even so, the risk of having another baby with trisomy 13 is usually very low.

A trisomy 13 translocation is not associated with mom’s age, but is a hereditary chromosome problem. The risk of recurrence in some types of (balanced) translocations can be quite high.

Dr. Alan Greene

Dr. Greene is the founder of DrGreene.com (cited by the AMA as “the pioneer physician Web site”), a practicing pediatrician, father of four, & author of Raising Baby Green & Feeding Baby Green. He appears frequently in the media including such venues as the The New York Times, the TODAY Show, Good Morning America, & the Dr. Oz Show.

  1. Ashley Liberda

    I did a quad chromosome screening from Counsyl and it came back there was a 23% chance my baby has Trisomy 13. I have to do a CVS scan to see if my baby does have it or not. I’m very scared. I’m staying positive as 77% chance things are ok is a positive number. Does any one have times where the test is false positive? Also T13 is so rare but they said that 23% is very high and T13 positive is something they never see so they are concerned.

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  2. ThereseAnn

    Trisomy 13 is NOT universally fatal. There are many survivors living with trisomy 13. Even full – complete Trisomy 13 as my own child. Natalia will be 16 years this August 2016.

    There is a wealthy of information and the most current studies and medical journals on the SOFT Support Organization for Trisomy 18, 13 and Related disorders. http://www.trisomy.org They have a facebook community where trisomy families gather to support each other with all trisomy variations.

    There is also a Living with Trisomy 13 Community on Facebook on a Public Group. Many long term survivors within this community and many who have used medical interventions to help keep their children comfortable within the medical conditions that come with Patau Syndrome and the unique issues of their child.
    http://www.livingwithtrisomy13.org

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    • Thank you so much for sharing these resources and happy sweet, sweet 16 to Natalia!

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  3. Sharilyn Jussila

    We received a blood test result (NIPT testing) of positive for Trisomy 13 just a few days ago. There were no markers found with a 2D ultrasound the next day and we are 16 weeks along.

    Some of the things the ultrasound doc said was a normal heart rate and size of baby, kidneys were not enlarged, stomach was normal, stomach cavity was all enclosed, brain has a definite line formed down the center, no evidence of extra digits or club feet, no thickening of the skin on the back of the neck area, no cleft palate.

    We have received conflicting information about this blood testing. The testing facilities advertise 1% false positive rate, however the genetic counselor said in the study there were 10,000 women, and 251 of the women tested positive from NIPT blood testing for Trisomy 13, yet only 7 of the babies born had the condition. This leads the genetic counselor to believe it’s a 92% false positive rate.

    Have you had any experience with NIPT blood testing with your patients, and if not, how early does Trisomy 13 show up in ultrasounds? I guess you could say I’m freaking out and would love and appreciate any information you can provide! We do not want to do an amniocentesis.

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    • melissa

      The NIPT is NOT that accurate. I had the NIPT test done for down syndrome (which is what is easy created for). My baby does have down syndrome so I will say it’s not inaccurate but I did a lot of research and was even part of a study. It is the MOST accurate for down syndrome at about 80%. But T13 and T18 are much lower. They need a combination of imaging and the test. There was a girl I was in the study with who was told her baby would have T18 and almost aborted but no abnormalities in the ultrasound. Her doc told her to wait since the test was so new and we don’t have enough studies to know the actual numbers. Her baby is healthy. No T18. I hate that stupid NIPT test. That 99% is a lie. Your baby may have T13 but it is not nearly as accurate as they say.

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