Chromosome 13q duplication is a chromosome abnormality that occurs when there is an extra (duplicated) copy of genetic material on the long arm (q) of chromosome 13. The severity of the condition and the signs and symptoms depend on the size and location of the duplication and which genes are involved. Features that often occur in people with Chromosome 13q duplication include developmental delay, intellectual disability, behavioral problems and distinctive facial features. Chromosome testing of both parents can provide more information on whether or not the duplication was inherited. In most cases, parents do not have any chromosomal anomaly. However, sometimes one parent is found to have a balanced translocation, where a piece of a chromosome has broken off and attached to another one with no gain or loss of genetic material. The balanced translocation normally does not cause any signs or symptoms, but it increases the risk for having an affected child with a chromosomal anomaly like a duplication.