Chromosome 3p duplication

Alternate names

Duplication 3p; Trisomy 3p; 3p duplication; 3p trisomy; Partial trisomy 3p

Definition

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.

Cause

• 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.

Inheritance

• 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.

Signs and symptoms

The signs and symptoms of chromosome 3p duplication vary but may include:

• Developmental delay
• Intellectual disability
• Hypotonia (poor muscle tone)
• Cleft lip and palate
• Behavioral problems
• Short stature
• Microcephaly (unusually small head)
• Gastrointestinal abnormalities
• Seizures
• Congenital heart defects
• Distinctive facial features (i.e. wide-spaced eyes, full cheeks, depressed nasal bridge, etc)
• Genital abnormalities

Diagnosis

There are several different specialized tests that can be used to diagnose a chromosome 3p duplication. These include: Several types of genetic tests can identify chromosome disorders:

• Karyotype - a karyotype is a laboratory test that produces an image of a person's chromosomes. This test can be used to diagnose large deletions.
• 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 deletions 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 deletion of a specific region of 4q.
• Array CGH - a technology that detects deletions that are too small to be seen on karyotype.

Treatment

Treatment is directed toward the specific signs and symptoms present in each individual.

NIH genetic and rare disease info

• NIH info on Chromosome 3p duplication

Chromosome 3p duplication is a rare disease.

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