Chromosome 3q duplication

Alternate names

Trisomy 3q; Duplication 3q; Chromosome 3, trisomy 3q

Definition

Chromosome 3q duplication is a chromosome abnormality that occurs when there is an extra copy of genetic material on the long arm (q) of chromosome 3.

Cause

This condition occurs when there is an extra copy of genetic material on the long arm (q) of chromosome 3.

Inheritance

• Chromosome 3q duplication can be de novo (not inherited and occurring for the first time), or inherited from a parent with a chromosomal rearrangement such as a balanced translocation.
• In most cases, it occurs as part of an unbalanced translocation, which means that abnormalities of other chromosomes are also present.

Signs and symptoms

• 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 may be present in a person with a chromosome 3q duplication include distinctive facial features, hirsutism (excessive hair growth in women), small head size (microcephaly), intellectual disability, slowed growth, and abnormalities of the hands, feet, genitourinary system, kidneys, and/or heart.
• Various other neurologic abnormalities or birth defects affecting other parts of the body may also occur.
• About one third of babies with chromosome 3q duplication do not survive past the first year of life, often due to heart defects or infections.

Diagnosis

Chromosome disorders may be suspected in people who have developmental delays, intellectual disabilities and/or physical abnormalities.

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 3q duplication

Chromosome 3q duplication is a rare disease.

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