Definition - What does Balanced Translocation mean?
A balanced translocation is a condition in which sections of two chromosomes join at incorrect positions, despite the number of chromosomes being normal. People with a balanced translocation usually do not have any health problems; however, they may experience difficulty having children. A balanced translocation is seen 1 in 500 people and can affect both males and females.
FertilitySmarts explains Balanced Translocation
What causes a chromosome to break off and rejoin at an abnormal location is not known. This swapping may occur as part of the natural process during the formation of a sperm or an egg cell or immediately after fertilization. A balanced translocation may be inherited from the parent, or at other times, a balanced translocation arises as an entirely new phenomenon in the fetus, i.e. without any parent affected.
Since individuals with a balanced translocation usually do not experience any major health issues, they may remain undiagnosed until they have a child born with a chromosome abnormality or until they sustain multiple miscarriages, and/or repeated IVF failures. Although the chromosome number is normal, a loss or gain of an extra genetic material in the egg or sperm during cell division may contribute to the reduced fertility potential in an individual with a balanced translocation.
When balanced translocation is the culprit behind infertility, the affected couple may opt for preimplantation genetic diagnosis (PGD). PGD can help determine if the chromosomes of the embryos conceived via IVF have acquired any unusual translocation from the affected parent. It ensures the transfer of only balanced or normal chromosomes, increasing the odds of a normal pregnancy.
A balanced translocation is diagnosed through a blood test called karyotyping in which blood samples from both the partners are analyzed for the translocation.