translokatsiooni

Translokatsiooni, or translocation, is a chromosome abnormality in which a segment of one chromosome is relocated to another chromosome. It can occur between non-homologous chromosomes (reciprocal translocation) or within the same chromosome (intra-chromosomal translocation); Robertsonian translocations are a related form that involves fusion of two acrocentric chromosomes.

Reciprocal translocations involve an exchange of segments between chromosomes without a net gain or loss of genetic material for the carrier, who is often phenotypically normal. However, during reproduction, unbalanced gametes can be produced, increasing the risk of miscarriage or offspring with developmental disorders or congenital anomalies.

Robertsonian translocations result from the fusion of two acrocentric chromosomes at the centromere and typically reduce the chromosome number by one. Carriers are usually balanced and healthy, but they have a higher risk of unbalanced zygotes that can lead to conditions such as Down syndrome depending on the chromosomes involved.

Translocations can also contribute to disease through disruption of genes at breakpoints or by creating fusion genes with oncogenic potential. Somatic translocations are common in cancer and are diagnostic and therapeutic targets; well-known examples include the Philadelphia chromosome t(9;22) BCR-ABL in chronic myeloid leukemia, t(8;14) in Burkitt lymphoma, and t(11;14) in mantle cell lymphoma.

Detection and characterization rely on cytogenetic and molecular techniques such as karyotyping, fluorescence in situ hybridization (FISH), array CGH, and sequencing. Genetic counseling informs affected individuals and couples about reproductive risks and options, including preimplantation genetic diagnosis.