This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Chromosome 20p duplication is a rare chromosome abnormality that occurs when there is an extra copy (duplication) of genetic material on the short arm (p) of chromosome 20. The severity of the condition and the signs and symptoms depend on the size and location of the duplication and which genes are involved. In general, smaller duplications are less severe than larger duplications.
Very few cases of chromosome 20p duplication have been reported. The majority of those have been partial duplications (involving only part of the p arm) and have occurred as part of a translocation (along with a deletion on another chromosome). Therefore, it is hard to know which symptoms in people with a 20p duplication have been due to the duplication specifically. Signs and symptoms that have been reported in people with chromosome 20p duplication include intellectual disability, developmental delay, speech delay, poor coordination, dental problems, spinal bone abnormalities, distinctive facial features, and heart problems.
Most cases of chromosome 20p duplication have resulted from a healthy parent having a chromosomal balanced translocation or inversion (when a piece of a chromosome is facing the wrong direction). When a parent has one of these, there is an increased risk to have another child with a chromosome abnormality. Some chromosome 20p duplications have resulted from a random genetic error (not inherited), in which both parents have normal chromosomes. In these cases, it is unlikely the parents would have another child with a chromosome abnormality.
Treatment for chromosome 20p duplications depends on the signs and symptoms present in each person.
For more information, visit GARD.