Chromosome 3p duplication

People with chromosome 3p duplication have an extra (duplicate) copy of the genetic material located on the short arm (p) of chromosome 3 in each cell. The features associated with the condition vary significantly from person to person depending on the size and location of the duplication and which genes are involved.

In some cases, this duplication is inherited from a parent with a balanced translocation. Other cases are considered " de novo" and occur sporadically as a random event when the egg or the sperm is made. There is nothing that a person can do to cause or prevent this duplication from happening.

There are several different specialized tests that can be used to diagnose a chromosome 3p duplication. These include:

• Karyotype - a karyotype is a laboratory test that produces an image of a person's chromosomes. This test can be used to diagnose large duplications.
• FISH - a laboratory technique that is used to detect and locate a specific DNA sequence on a chromosome. During FISH, a chromosome is exposed to a small DNA sequence called a probe that has a fluorescent molecule attached to it. The probe sequence binds to its corresponding sequence on the chromosome. This test can be used in combination with karyotyping for duplications that are too small to be seen on karyotype, alone. However, FISH is only useful if the person ordering the test suspects there is a duplication of a specific region of 3p.
• Array CGH - a technology that detects duplications that are too small to be seen on karyotype.

Chromosome 3p duplication can be de novo or inherited from a parent with a balanced translocation.

" De novo " duplications occur sporadically as a random event during the formation of the egg or sperm. In these cases, a person would have no family history of the condition but could pass the duplication on to children.

Other cases of chromosome 3p duplication are the result of a balanced translocation in one of the parents. Carriers of a balanced translocation generally do not have any unusual symptoms or health problems; however, they have an increased risk of having children with a chromosome abnormality. To read more about balanced translocations, click here.

Chromosome 3p duplication is a chromosome abnormality that occurs when there is an extra copy of genetic material on the short arm (p) of chromosome 3. 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 3p duplication include developmental delay, intellectual disability, behavioral problems and distinctive facial features. Chromosome 3p duplication can be de novo or inherited from a parent with a balanced translocation. Treatment is based on the signs and symptoms present in each person.