Chromosome 4q duplication is a chromosome abnormality characterized by an extra copy (duplication) of genetic material on the long arm (q) of chromosome 4. The severity and specific symptoms depend on the size and location of the duplication, and which genes are involved. Features that have been described in some people with chromosome 4q duplication include developmental delay, intellectual disability, behavioral problems, birth defects, and distinctive facial features. Most cases are inherited from an unaffected parent with a chromosomal rearrangement called a balanced translocation. Some cases are not inherited and occur sporadically. Treatment is based on the signs and symptoms present in each person.

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.

We encourage you to view Unique's guide for people and families with a chromosome 4q duplication. The information they provide is drawn from what is known about 43 people with a chromosome 4q duplication.

People with questions about prognosis for themselves or family members are encouraged to speak with their doctors about how their signs and symptoms may affect their health and quality of life.