Chromosome 4q duplication

Alternate names

Duplication 4q; Trisomy 4q; 4q duplication; 4q trisomy; Partial trisomy 4q

Definition

Chromosome 4q duplication is a chromosome abnormality characterized by an extra copy (duplication) of genetic material on the long arm (q) of chromosome 4.

File:Human chromosome 4 ideogram.svg

Cause

This condition occurs when there is an extra copy (duplication) of genetic material on the long arm (q) of chromosome 4.

Inheritance

Most cases are inherited from an unaffected parent with a chromosomal rearrangement called a balanced translocation. Some cases are not inherited and occur sporadically.

Signs and symptoms

• The signs and symptoms associated with having a chromosome 4q duplication may depend on the size and location of the duplication; this affects which genes are involved.
• Since few cases of 4q duplication have been described in the literature, it is difficult to predict severity or the specific features that a person will have.
• Someone with a small duplication may be very mildly affected and have no developmental delays.
• Others, even within the same family, may have varying degrees of developmental delay, any of several types of birth defects, and/or distinctive facial features.
• While very few cases have been described, it seems that those with a very small duplication of material close to the middle of the chromosome (called a proximal duplication) are usually healthy with developmental delay and/or learning difficulties.
• Larger proximal duplications may be associated with heart or kidney problems.
• When the duplication involves material closer to the tip of the chromosome (called a distal duplication), it may be associated with thumb and kidney abnormalities, developmental delay, and distinctive facial features.
• If a chromosome 4q duplication occurs with another chromosome abnormality (such as a deletion of part of another chromosome), the severity and features in an affected person may differ and will depend on the effects of the other chromosome abnormality as well.

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:

• Karyotyping
• Microarray (also called array CGH)
• Fluorescence in situ hybridization (FISH)

Treatment

Treatment is based on the signs and symptoms present in each person.

Prognosis

• The long-term outlook (prognosis) for people with a chromosome 4q duplication depends on the size and location of the duplication.
• This affects which specific genes are involved, and how many genes are duplicated.
• Some people with a 4q duplication may be born healthy and develop well, while others may be born with any of several types of birth defects that can lead to severe complications.
• Therefore, it is not possible to predict how one person will be affected. Additionally, people with the same 4q duplication (the same location and size) may be affected very differently - even within the same family.

NIH genetic and rare disease info

• NIH info on Chromosome 4q duplication

Chromosome 4q duplication is a rare disease.