What happens because of the gene change in trisomy 20p?
An extra chromosome 20p can cause a range of symptoms. These include specific facial features, bone problems, heart defects, and abnormal kidneys. As children with trisomy 20p grow, they usually reach milestones, such as walking, later than other children. They also have intellectual disability and may need to be in special classes. Children with trisomy 20p usually grow at a normal rate, so they will not be significantly shorter or taller than peers. The symptoms can be more or less severe. This depends on how much of chromosome 20p is duplicated. Usually, having more of the chromosome will result in more serious symptoms.
Scientists and doctors are not sure exactly how having an extra piece of the chromosome causes these symptoms. The extra set of instructions may interfere with normal development.
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Does anything make trisomy 20p worse?
There is nothing that makes the symptoms of trisomy 20p worse. However, early intervention can result in better outcomes for a person with trisomy 20p. For example, the affected person may need speech and physical therapy.
Is there a predisposition or a cause for trisomy 20p?
Having an extra copy of chromosome 20p in the cells of the body causes trisomy 20p. No other factor is necessary in order to show the symptoms.
Most cases of trisomy 20p are the result of a chromosome rearrangement. This usually takes place when the chromosomes combine to create a new baby. It is called a translocation. This means that some chromosome information has been moved from the usual location to a new location. It can cause an extra piece of chromosome 20p to be present in the baby's cells.
In a few cases, a parent's chromosome may be rearranged (called an inversion). The parent has the normal amount of chromosome 20p, but their children can be at risk for having more or less of the normal amount of chromosome 20p.
- Oppenheimer S, Dignan P, Soukup S. Partial trisomy 20p: familial occurrence. Am J Med Genet. 2000 Dec 11;95(4):316-9. Review.
- Chaabouni M, Turleau C, Karboul L, Jemaa LB, Maazoul F, Attié-Bitach T, Romana S, Chaabouni H. De novo trisomy 20p of paternal origin. Am J Med Genet A. 2007 May 15;143A(10):1100-3.