Chromosomal translocation

A chromosome rearrangement in which a DNA segment moves to a different chromosome or a different position within the same chromosome. Translocations can be balanced, with no net DNA gain or loss, or unbalanced.

Reciprocal translocation: A chromosome rearrangement in which segments from two nonhomologous chromosomes exchange places. It is the classic form involving breaks in two chromosomes and an exchange of their segments.
Philadelphia chromosome: An abnormal chromosome 22 carrying a BCR::ABL1 fusion, created by a reciprocal translocation with chromosome 9. This specific translocation is a defining genetic marker of most chronic myeloid leukemia.
Balanced chromosomal rearrangement: A chromosome structural change with no apparent net gain or loss of genetic material. Many carriers have balanced translocations and no direct symptoms, despite risks during reproduction.
Chromosome: A DNA molecule packaged with proteins that carries genetic information in a cell. Translocations rearrange segments of these organized DNA structures.
Chromosomal deletion: A chromosome rearrangement in which a segment is lost. A deletion removes DNA, whereas a balanced translocation can relocate DNA without net loss.
Robertsonian translocation: A rearrangement in which two acrocentric chromosomes fuse near their centromeres, usually losing their short arms. It shows how whole chromosome arms can join in a translocation.
BCR::ABL1: A fusion gene encoding a constitutively active tyrosine kinase, usually formed by translocation between chromosomes 9 and 22. It illustrates how a translocation can create an oncogenic fusion protein.
Unbalanced chromosomal rearrangement: A chromosome structural change that results in a net gain or loss of genetic material. Unbalanced products can arise when a translocation carrier forms eggs or sperm.
Chromosome banding: A staining method that produces characteristic light and dark patterns along chromosomes for identification. Banding patterns help locate structural changes and recognize exchanged chromosome segments.
Chromosomal duplication: A chromosome rearrangement in which a segment is copied, increasing its genomic dosage. A duplication changes segment copy number rather than primarily changing its location.

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