partial duplication of the long arm of chromosome 6 (MONDO_0016957) can be described as follows. Chromosome 6q duplication is a chromosome abnormality that occurs when there is an extra copy of genetic material on the long arm (q) of chromosome 6. 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 6q duplication include developmental delay, intellectual disability, behavioral problems and distinctive facial features. In most cases, chromosome 6q duplication occurs de novo or is inherited from a parent with a chromosomal rearrangement such as a balanced translocation. Rarely, it is inherited from a parent with the same duplication. Treatment is based on the signs and symptoms present in each person. Also known as: partial duplication of chromosome 6q, partial duplication of the long arm of chromosome type 6, partial trisomy of chromosome 6q, partial trisomy of the long arm of chromosome 6.