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Inherited Disorders and Birth Defects

Can we have more children?

10/13/2008

Question:

I recently gave birth to little girl who had patau sydrome. Because of this she died. This was utterly devastateing. Me and my partner are now trying for a another child. I recived a letter from my doctor saying that my girls blood test results indicate that me and my partner should have blood tests. Again this has devastated me. The thought of not having another child kills me. If me or my partner is a carrier, what are the chances of us having a healthy baby?

Answer:

First, please accept my deepest sympathy on the death of your daughter. And please accept my sincerest apologies for not responding to your questions sooner.

Patau syndrome is due to an extra chromosome 13 - it is usually called Trisomy 13. As you know, babies born with Trisomy 13 have many problems and birth defects and usually die within the first few months of life.

In most cases, Trisomy 13 is due to having 3 # 13 chromosomes instead of 2 # 13 chromosomes so that the baby has 47 chromosomes instead of the normal number of 46 chromosomes. The chance of having another baby with Patau syndrome (trisomy 13) is very low - we would not expect it to happen again.

However, in a small percentage of babies with Patau syndrome, the baby inherits an unbalanced translocation that involves chromosome 13 and this leads to Patau syndrome.

A translocation is when two pieces of chromosomes break off and switch places with each other. An unbalanced translocation happens when the chromosomes break and switch places so that there is a loss or duplication of chromosome material - such as having an extra 13 chromosome. This leads to extra and / or missing genetic information that can lead to miscarriages, birth defects and problems such as mental retardation.

If all the chromosomal material is present, but it has been rearranged - that is, pieces of the chromosomes have switched places (translocated) - however, there is no extra or missing chromosome material - this person has what is called a balanced translocation. This person should have no health problems since all the chromosomal material needed is present and functioning properly. However, a person who is a balanced translocation carrier can have babies that have unbalanced chromosome arrangements.

Your doctor may want to test you and your partner to see if you could be a carrier of a balanced translocation that involves chromosome 13. If you or your partner is a carrier, you do have a small increased chance of having another baby with Patau syndrome or have a miscarriage. There is no way to tell if someone is a translocation carrier except to look at his or her blood.

You have asked excellent questions. I would very much recommend that you talk to a genetic counselor or geneticist. They have expertise in this area. You can ask your doctor for a referral or you can locate a genetics center near you at the National Society of Genetic Counselors Resources center website listed below.

Again, please accept my deep sympathy for your loss.

Related Resources:

National Society of Genetic Counselors Resource Center

For more information:

Go to the Inherited Disorders and Birth Defects health topic, where you can:

Response by:

Anne   Matthews, RN, PhD Anne Matthews, RN, PhD
Associate Professor of Genetics
School of Medicine
Case Western Reserve University