What type of mutation occurs when a gene is repeated?

A duplication mutation occurs when a segment of DNA is copied and added to the genome, resulting in the repetition of a gene or part of a gene. This can lead to changes in the expression of the affected gene, potentially resulting in increased gene dosage, which may have various effects on an organism's phenotype. In some cases, duplication mutations can contribute to evolutionary processes by providing additional genetic material that can evolve new functions over time.

Other types of mutations mentioned do not involve the replication of genes. For instance, inversion mutations occur when a segment of DNA is flipped and reintegrated into the chromosome, altering the gene's orientation but not its quantity. Deletion mutations remove segments of DNA, resulting in a loss of genetic information. Insertions typically involve adding new DNA sequences rather than repeating existing ones, and translocations involve segments of DNA moving from one location to another in the genome, fundamentally altering the arrangement of genetic material without duplicating it.