Partial deletion of the short arm of chromosome 3

Alternate names

Partial deletion 3p; 3p partial deletion; Partial monosomy 3p; Partial deletion of chromosome 3p; Partial monosomy of chromosome 3p; Partial monosomy of the short arm of chromosome 3

Definition

Chromosome 3p partial deletion is a chromosome abnormality that affects many different parts of the body. People with this condition are missing genetic material located on the short arm (p) of chromosome 3 in each cell.

Cause

• People with chromosome 3p partial deletion are missing 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 deletion and which genes are involved.
• In many cases, this deletion occurs 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 deletion from happening.

Inheritance

• Most cases of chromosome 3p deletion are not inherited.
• The condition generally 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 it on to children.
• Rarely, chromosome 3p deletion is passed down from parent to child.
• Some of these cases 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.
• In other cases, the parent may be missing genetic material located on the short arm (p) of chromosome 3 in some (mosaicism) or all of their cells. Because the symptoms and severity can vary between family members, the parent may not have any obvious symptoms or may only be mildly affected.

Signs and symptoms

The severity of chromosome 3p deletion and the associated signs and symptoms vary based on the size and location of the deletion and which genes are involved. Some affected people may have no features of the condition, while others are very severely affected.

Signs and symptoms may include:

• Developmental delay
• Intellectual disability
• Autism spectrum disorder
• Low birth weight
• Feeding problems
• Hypotonia
• Distinctive craniofacial features (such as wide-spaced eyes; low-set ears; cleft lip and/or palate; ptosis)
• Microcephaly (small head)
• Seizures
• Hearing loss
• Congenital heart defects
• Scoliosis or other skeletal problems
• Extra fingers and/or toes
• Kidney problems
• Genital abnormalities

Diagnosis

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

• Array CGH - a technology that detects deletions that are too small to be seen on karyotype.

Treatment

• Because chromosome 3p 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.
• A feeding tube may be recommended in infants with feeding difficulties who have trouble putting on weight.
• 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.

Prognosis

• The long-term outlook (prognosis) for people with chromosome 3p 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.

NIH genetic and rare disease info

• NIH info on Partial deletion of the short arm of chromosome 3

Partial deletion of the short arm of chromosome 3 is a rare disease.

Partial deletion of the short arm of chromosome 3 Resources
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