chromodomain helicase DNA binding protein 3
The CHD3 gene provides instructions for making a protein that regulates gene activity (expression) by a process known as chromatin remodeling. Chromatin is the complex of DNA and protein 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. Chromatin remodeling is one way gene expression is regulated during development. The CHD3 protein helps with chromatin remodeling by moving components called nucleosomes, that help bundle DNA in a tight package. Moving nucleosomes helps make DNA more accessible for gene expression. The CHD3 protein provides energy for this remodeling by breaking down a molecule called ATP.
Through its ability to regulate gene activity, the CHD3 protein is involved in many processes during development, including maintenance of the structure and integrity of DNA, the maturation process that determines the type of cell an immature cell will ultimately become (cell fate determination), and the growth of cells as they progress through the step-by-step process they take to replicate themselves (the cell cycle).
More than 25 mutations in the CHD3 gene have been found to cause Snijders Blok-Campeau syndrome. This condition is characterized by intellectual disability, developmental delay, speech delay, and distinctive facial features.
Most CHD3 gene mutations change single protein building blocks (amino acids) in the CHD3 protein. The majority of mutations alter an area of the protein that is involved in breaking down ATP to provide the energy for chromatin remodeling. CHD3 gene mutations can either increase or decrease the protein's chromatin remodeling activity. These changes seem to affect the activity of genes that direct the development of many different organs and tissues before birth. It is unclear how increased and decreased protein function both lead to the signs and symptoms of Snijders Blok-Campeau syndrome.