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Inherited Disorders and Birth Defects

Miscarriage- unbalanced translocation

06/05/2010

Question:

Hi,

I have had 2 m/c in the first trimester in last year. DNC`s were done and the results of the first m/c was trisomy 15. The next m/c results were unbalanced translocation. Both my partner and I have had karyotyping done a few years back and are both genetically normal with no balanced translocations. My question is, could we have a balanced translocation that wasn`t picked up on our karyotype tests? Or is it more likely that this was a random unbalanced translocation? I am wondering if I should retest?

Answer:

Most translocations are random and only a small portion are inherited from a parent. Also, it is not uncommon to see pregnancies that miscarry having different types of chromosome abnormalities, such as in your case in which you had a pregnancy that had a trisomy 15 and another pregnancy that miscarried with an unbalanced chromosomal translocation.

Almost all of the time, a good cytogenetics lab should be able to identify a balanced translocation, particularly if they know what the specific unbalanced translocation was in your miscarriage. However, while the accuracy of a karyotype is usually better than 99%, it is not 100%. While highly unlikely, something could have been missed.

If you have not already done so, I would recommend that you talk to a genetic counselor or geneticist about your concerns. You can ask your doctor to refer you or find a genetics center near you at the website below.

Related Resources:

National Society of Genetic Cousnelors 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