Translocation is a type of abnormal change in the structure of a chromosome. It occurs when a part of one chromosome breaks off and sticks to another chromosome.
There are two types of translocation. In a balanced translocation, equal parts of the two chromosomes are exchanged, so there is no extra or missing genetic information. In an unbalanced translocation, the exchange involves unequal portions of chromosome and leads to extra or missing genes.
Translocations are indicated using a lower case "t" with the two chromosomes involved in brackets. For example, a translocation between chromosomes 9 and 22 would be indicated by t(9;22).
Translocations are a type of damage that may cause a gene to turn into a cancer-causing gene. Scientists do not know what causes these chromosome changes to occur.
Some translocations that are involved in blood cancers are:
- t(8;21) -- Acute myeloblastic leukemia with maturation
- t(9;22), know as the “Philadelphia Chromosome” -- Chronic myelogenous leukemia (CML) and Acute lymphocytic leukemia (ALL)
- t(15;17) -- Acute promyelocytic leukemia (APL)
- t(12;15), t(1;12) -- Acute myelogenous leukemia (AML)
- t(2;5) -- Anaplastic large cell lymphoma
- t(8;14) -- Burkitt's lymphoma
- t(11;14) -- Mantle cell lymphoma
- t(14;18) -- Follicular lymphoma
Physicians discover chromosome translocation when doing genetic analysis of biopsy samples. It helps them to identify the disease, plan therapy, and predict treatment outcomes.