chromodomain helicase DNA binding protein 2
The CHD2 gene provides instructions for making a protein called chromodomain DNA helicase protein 2. This protein is found in cells throughout the body and regulates gene activity (expression) through a process known as chromatin remodeling. Chromatin is the complex of DNA and proteins that packages DNA into chromosomes. The structure of chromatin can be changed (remodeled) to alter how tightly DNA is packaged. When DNA is tightly packed, gene expression is lower than when DNA is loosely packed. Chromodomain DNA helicase protein 2 appears to play an important role in the brain, although its function is not well understood. Research suggests that it may help control development or functioning of nerve cells (neurons).
At least 30 mutations in the CHD2 gene have been found to cause CHD2 myoclonic encephalopathy, a condition characterized by recurrent seizures (epilepsy), abnormal brain function (encephalopathy), and intellectual disability beginning in childhood. About half of these mutations delete pieces of DNA from the CHD2 gene. These and other CHD2 gene mutations either prevent the production of any chromodomain DNA helicase protein 2 or lead to the production of a nonfunctional version of the protein. As a result, chromatin remodeling and gene expression normally regulated by the chromodomain DNA helicase protein 2 are disrupted. It is unclear why CHD2 gene mutations seem to only affect nerve cells in the brain or how they lead to the signs and symptoms of CHD2 myoclonic encephalopathy.
At least nine CHD2 gene mutations have been identified in people with autism spectrum disorder (ASD), a varied condition characterized by impaired social skills, communication problems, and repetitive behaviors. Mutations in the CHD2 gene impair the function of the CHD2 protein, resulting in small changes in the expression of many genes, the effects of which combine to affect brain development and increase the risk of ASD. Normal variations in other genes, as well as environmental risk factors, such as parental age, birth complications, and others that have not been identified, also affect an individual's risk of developing this complex condition.
- ATP-dependent helicase CHD2