Tandem duplication

Tandem duplication is a type of mutation that occurs when a sequence of DNA is repeated in the genome. This can result in the duplication of a single gene or a larger segment of the chromosome. Tandem duplications can have significant effects on genetic diversity and evolution, and can also lead to the development of certain genetic disorders.

Mechanism

Tandem duplications occur during DNA replication, when the replication machinery mistakenly copies a segment of DNA more than once. This can happen due to errors in the DNA polymerase enzyme, which is responsible for copying the DNA sequence. The duplicated segment is then inserted back into the genome in a direct repeat, resulting in a tandem duplication.

Effects

The effects of tandem duplications can vary widely, depending on the size of the duplicated segment and its location in the genome. Small duplications may have little to no effect, while larger duplications can disrupt the function of genes and lead to genetic disorders. For example, tandem duplications in the BRCA1 gene have been associated with an increased risk of breast cancer and ovarian cancer.

Tandem duplications can also contribute to genetic diversity and evolution. By creating copies of genes, they provide raw material for evolution to act upon. These duplicated genes can then diverge over time, leading to the development of new functions and traits.

Detection

Tandem duplications can be detected using various genetic testing methods. These include comparative genomic hybridization (CGH), fluorescence in situ hybridization (FISH), and next-generation sequencing (NGS). These techniques can identify the presence of duplicated segments in the genome, and can also determine their size and location.

See also

• Copy-number variation
• Genetic recombination
• Genetic variation
• Genomic instability