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Inherited Disorders and Birth Defects

Translocation chromosome

12/22/2006

Question:

I need to know what chromosome 7 does?

When I was pregnant chromosome 7 did a translocation and it didn’t line up correctly.

Now my son is 6 years old and he is hearing problems & eye problems. Could this be caused by Chromosome 7?

Answer:

There are almost 1,500 genes on chromosome 7 that code for hundreds of different proteins and other functions. While there is a gene on chromosome 7 that is known to cause deafness, it is impossible for me to say that is the basis for your son’s hearing problems. Also, if your son has an unbalanced translocation involving chromosome 7 - there probably are many genes that are involved - not just one gene.

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, but 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. 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.

However, there can be problems if some of the chromosomal material that was switched is lost or duplicated when the chromosomes broke and the switch took place – then there is extra and / or missing information that can lead to birth defects and cognitive problems such as delayed development or mental retardation. This is an unbalanced translocation.

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.

If your son has not already seen a geneticist or genetic counselor, I would highly recommend that you have your doctor make a referral or you can locate a genetics center near you by using the National Society of Genetic Counselors’ Resource website listed below. The geneticist would be able to provide you with information specifically for your son based on his specific problems with chromosome 7.

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