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Inherited Disorders and Birth Defects

Balanced translocation

02/07/2007

Question:

Hi I had my first child at 40 and he is now 5.I found out that he had #11 and #20 the top part of his chromosome missing. They tested me and said mine were the same so we have a balanced translocation. My son is fine and so am I. Can you please tell me what affect on us it may have or if this type of translocation is common and what if any ailments it may produce? I also miss carried with a boy at 43. We are still trying to have another child at 46. I know ha-ha. Thank you.

Answer:

As you probably are aware, chromosomal translocations can be somewhat tricky to understand. A balanced translocation occurs when two pieces of chromosomes break off and switch places with each other. If all the chromosomal material is present, just rearranged – that is, switched places (translocated) - this person should have no health problems since all the chromosomal material needed is present and functioning properly. This is called a balanced translocation. Also, you would not expect to have any health problems develop because of a balanced translocation. There is no way to tell whether or not a person has one of these rearrangements unless you look at his or her blood to examine the chromosomes.

For the person that has a balanced translocation, (such as you and your son), when that person forms eggs or sperm, some of the chromosomal material can be lost or duplicated so that there is extra and / or missing genetic information. This is called an unbalanced chromosome translocation. This leads to miscarriage in most cases. However, in a very small percentage of pregnancies where there is an unbalanced chromosome translocation such as between # 11 and # 20, it could result in a live birth. This baby could have birth defects and mental retardation.

The specific types of problems or birth defects would depend on the specific areas of the chromosomes that were lost or duplicated in the chromosomes that are translocated and what specific genes are located at these sites. For many unbalanced rearrangements (translocations) it is not possible to predict what abnormalities to expect; for others the medical literature may provide information.

If you have not already done so, I would recommend that you discuss these issues with a genetic counselor or geneticist who have a great deal of expertise in this area. You can locate a genetics center near you at the National Society of Genetic Counselors’ Resource website below.

Related Resources:

National Society of Genetic Counselors Resource Center

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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