Final answer:
A duplication in genetics refers to the addition of a chromosome segment, resulting in the replication of a specific DNA segment and potentially causing a genomic duplication disorder.
Step-by-step explanation:
A duplication in genetics is best defined as the addition of a chromosome segment. This process leads to a segment of DNA being repeated, which results in a longer chromosome as the genome acquires extra copies of the genes present in the duplicated segment. An example of this would be, during interphase of the cell cycle, when the DNA duplication occurs to ensure each new cell receives an accurate copy of the genetic material. This replication creates two identical copies, known as sister chromatids, which are later separated during cell division. However, if a segment of the chromosome duplicates erroneously, it can lead to a condition known as a genomic duplication disorder, differing from other chromosome abnormalities such as trisomy where an entire chromosome is duplicated.