CHD7 gene
The CHD7 gene provides instructions for making a protein essential for chromatin remodeling and embryonic development, with mutations linked to conditions like CHARGE syndrome and Kallmann syndrome.
Normal Function
The CHD7 gene provides instructions for making a protein called chromodomain helicase DNA binding protein 7. This protein is found in many parts of the body before birth, including the eye, the inner ear, and the brain. In the brain, the CHD7 protein is active in several areas, including a bundle of nerve cells (neurons) called the olfactory bulb that is critical for the perception of odors.
The CHD7 protein belongs to a family of proteins that are thought to play a role in the organization of chromatin. Chromatin is the complex of DNA and protein that packages DNA into chromosomes. The CHD7 protein regulates the activity (expression) of several other genes through a process known as chromatin remodeling. 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.
Health Conditions Related to Genetic Changes
CHARGE syndrome
Mutations in the CHD7 gene cause CHARGE syndrome, a disorder that affects many areas of the body. CHARGE is an abbreviation for several of the features common in the disorder:
- Coloboma
- Heart defect
- Atresia choanae (also known as choanal atresia)
- Growth retardation
- Genital abnormality
- Ear abnormality
More than 600 mutations that can cause CHARGE syndrome have been identified. Most of these mutations lead to the production of an abnormal CHD7 protein that is broken down prematurely. Shortage of this protein is thought to disrupt chromatin remodeling and the regulation of gene expression during embryonic development.
Kallmann syndrome
More than 50 mutations in the CHD7 gene have been identified in people with Kallmann syndrome, a disorder characterized by the combination of hypogonadotropic hypogonadism (a condition affecting the production of hormones that direct sexual development) and an impaired sense of smell. Mutations in this gene account for 5 to 10 percent of all cases of Kallmann syndrome.
Many people with Kallmann syndrome caused by a CHD7 gene mutation have some features of CHARGE syndrome, such as abnormally shaped ears and hearing loss, though the symptoms tend to be much less severe. Researchers suspect that Kallmann syndrome resulting from a CHD7 mutation may represent a mild form of CHARGE syndrome.
Anophthalmia/Microphthalmia and Coloboma
The CHD7 gene is also associated with Anophthalmia/Microphthalmia and Coloboma.
Genomic Location
The CHD7 gene is found on chromosome 8.