Thursday, March 5, 2015
Inherited Disorders and Birth Defects
Translocation, 46xx (t1;9) (p31;q33)
What is the prognosis of fetus having translocation 46XX,(t1;9) (p31;q33) found on chormosomal culture done for a lady of maternal age 36? Should the fetus be terminated?
As you have written this translocation this is a female with a balanced translocation between chromosome 1 and chromosome 9. The (p31;q33) refers to where on chromosome 1 and 9 the exchange of material took place. This would be considered to be a balanced translocation.
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 due to the translocation since all the chromosomal material needed is present and functioning properly.
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 miscarriages, birth defects and cognitive problems such as mental retardation. This is an unbalanced translocation.
While there should be no problems if the translocation is balanced, on rare occasions, if the breaks in the chromosomes happen to be in the middle of a gene, it could disrupt normal functioning of that gene or genes. Usually when a fetus is found to have a translocation, the parents have their chromosomes analyzed to see if one of them may also be a carrier for the same balanced translocation.
I highly recommend that parents talk to their doctor about seeing a geneticist or genetic counselor to discuss in detail the meaning of a translocation found in a fetus. Parents can locate a genetics center through the National Society of Genetic Counselors' Resource website.
Anne Matthews, RN, PhD
Associate Professor of Genetics
School of Medicine
Case Western Reserve University