Chromosome 4q deletion

People with chromosome 4q deletion are missing genetic material located on the long arm (q) of chromosome 4 in each cell. Scientists suspect that many of the features seen in people affected by this condition are caused by the deletion and/or disruption of certain genes found on 4q. The severity of the condition and the associated signs and symptoms vary depending on the size and location of the deletion and which genes are involved. For example, deletion of the following genes may contribute to the features seen in some affected people:

• BMP3 - skeletal abnormalities and short stature
• SEC31A - distinctive craniofacial features
• PKD2 - kidney abnormalities
• GRID2, NEUROG2 - neurological problems such as seizures, hypotonia, and delayed motor development (i.e. sitting up, walking, etc)
• ANK2, HAND2 - heart defects and/or arrhythmias
• FGF2 - limb (arms and legs) abnormalities

Researchers are working to learn more about the other genes on 4q that may contribute to the features seen in people with a chromosome 4q deletion.

There are several different specialized tests that can be used to diagnose a chromosome 4q deletion. 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 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.

Chromosome 4q deletion is usually not inherited. The deletion often occurs sporadically as a random event during the formation of the egg or sperm. In this case, a person would have no family history of the condition but could pass the deletion on to children.

Rarely, this deletion is passed down from parent to child. However, the symptoms and severity can vary between family members.

The long-term outlook (prognosis) for people with chromosome 4q deletion varies from person to person. The severity of the condition and the associated signs and symptoms largely depend on the size and location of the deletion and the genes involved.

Because chromosome 4q deletion affects many different systems of the body, medical management is often provided by a team of doctors and other healthcare professionals. Treatment for this deletion varies based on the signs and symptoms present in each person. For example, babies with congenital heart defects and certain skeletal abnormalities may require surgery. Children with bone or muscle problems and/or delayed motor milestones (i.e. walking) may be referred for physical or occupational therapy. Certain medications may be prescribed to treat seizures. Special education services are often necessary for children with intellectual disability.

Please speak to your healthcare provider if you have any questions about your personal medical management plan.