Balanced translocation

Balanced translocation (also known as "chromosomal translocation") is a condition in which chromosomes are unusually rearranged. When balanced translocation occurs, a piece of the chromosome is broken off and attaches itself elsewhere. This can result in egg or sperm cells with missing or extraneous genetic material, possibly leading to fertility issues or miscarriage.

What is a balanced translocation?

A balanced translocation, also known as a reciprocal translocation, is a condition in which part of a chromosome (molecule of genetic material) breaks off and switches places with a section on another chromosome. This reciprocal material exchange between two different chromosomes may result in miscarriage or other fertility issues. Most people do not know they have this condition until they experience infertility.

Balanced translocation and male fertility

Studies show that balanced translocations in males may cause reductions in testicular volume and testosterone levels. This can contribute to azoospermia or oligozoospermia, making it more difficult to conceive a child.

Balanced translocations also increase the risk of miscarriage if the condition is found in either partner. Couples in which one partner has a balanced translocation have a 50% chance of pregnancy loss and a 20% risk of having children with chromosomal abnormalities. However, some people who carry balanced translocations can conceive naturally and have healthy children despite the condition.

A balanced translocation is diagnosed through a karyotype genetic test in which blood samples from both parents are examined.

Causes of balanced translocation

Balanced translocations can either be inherited from a parent or occur at the time of conception, due to a change that had arisen during the production of the egg or the sperm. Research suggests that most balanced translocations are inherited paternally, and they are more common in older fathers. Around 1 in 500 individuals carry a balanced translocation.

Treatment for balanced translocation

Though balanced translocations cannot be corrected, there are a number of ways a person can increase their chances of conceiving if they have this condition. One treatment is preimplantation genetic diagnosis, or PGD, in which the couple pairs in vitro fertilization (IVF) with genetic testing to detect translocations in their embryos. Another option is gamete or embryo donation. Because there is no genetic link to one or both parents, this option eliminates the risk for inherited translocations.

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