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Balanced Translocation and Recurrent Miscarriages

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Updated April 18, 2008

A chromosomal translocation is a condition in which part of a chromosome has broken off and reattached in another location. Translocations can be completely harmless or they can cause serious health problems, depending on the circumstances.

In the case of the former, many people can have translocations without being aware of the condition. This is usually the case for reciprocal (or balanced) translocation, a type of chromosomal translocation that increases the risk of recurrent miscarriages.

What Balanced Translocation Means:

In a balanced translocation, a person usually has all the genetic material necessary for normal growth -- a piece of a chromosome is merely broken off and attached to another one. However, when that person's cells divide to create egg or sperm cells for reproduction, the egg or sperm cells can end up with extra genetic material or missing genetic material, which could lead to miscarriage depending on which chromosome and genes are affected.

Incidence in Recurrent Miscarriages:

In about 4.5% of all couples with recurrent miscarriages, one or both parents has a balanced translocation. Research has shown that couples with balanced translocations are more likely to have miscarriages than couples without balanced translocations. There's some evidence that balanced translocations involving specific chromosomes are more likely to cause miscarriages than others.

Testing for Balanced Translocation:

Balanced translocation is diagnosed through a test called a karyotype in which blood samples from both parents are analyzed looking for the translocation. Some research suggests balanced translocation in the mother is most likely to be associated with recurrent miscarriages, but fathers can be carriers as well.

Treatment for Balanced Translocation:

There is no cure for balanced translocation, and in most cases, the only adverse effect on health is recurrent miscarriages. For couples affected by balanced translocation, odds are in favor of a successful pregnancy at some point, but repeated miscarriages can obviously be difficult to cope with emotionally.

In some cases, couples with balanced translocation can opt for a treatment called preimplantation genetic diagnosis (PGD). In PGD, the couple conceives via in-vitro fertilization along with gene testing of the embryos to be sure that they do not have an unbalanced translocation.

PGD is very expensive, however, and not covered by insurance much of the time, which is another reason why many couples are forced to keep trying without intervention.

Sources:

Lippman-Hand, A. and M. Vekemans, "Balanced translocations among couples with two or more spontaneous abortions: Are males and females equally likely to be carriers?" Human Genetics May 1983. Accessed 21 Mar 2008.

Sugiura-Ogasawara, Mayumi, Yasuhiko Ozaki, Takeshi Sato, Nobuhiro Suzumori, and Kaoru Suzomori, "Poor prognosis of recurrent aborters with maternal or paternal reciprocal translocations." Fertility and Sterility Feb 2004. Accessed 21 Mar 2008.

  1. About.com
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  3. Miscarriage / Pregnancy Loss
  4. Causes
  5. Two or More Miscarriages
  6. Balanced Translocation and Recurrent Miscarriage - How Balanced Translocation Causes Pregnancy Loss

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