Charge Syndrome is a specific collection of non-randomly occurring congenital anomalies. The acronym CHARGE actually stands for the major features of this syndrome. The letter C stands for coloboma of the eye, H is heart defects, A stands for atresia of the choanae, R is retarded growth and development, G stands for genital abnormalities and lastly letter E stands for ear anomalies and/deafness. The cause of this syndrome may be genetically heterogeneous, but most cases are not regular events of unknown cause.
The CHARGE Syndrome is genetically caused by a small deletion of chromosome 8. A tiny region on chromosome 8 appeared to contain and develop a new gene called CHD7. The mutation in CHD7 is found in about 60% of the patients. This syndrome can occur although the parent is not affected. Some of his or her sperm or egg cells carry the same CHD7 mutation can cause their child to have CHARGE Syndrome. Sometimes, in affected siblings, a mosaic mutation of CHD7 can be detected in one of the parents. A person having the CHARGE Syndrome has a risk of 50% to pass on the CHD7 mutation. But infertility is common in CHARGE Syndrome. So, a result of parent-to-child transmission is rare.
Location of CHD7
Cytogenetic Location: 8q12.2
Molecular Location on chromosome 8: base pairs 61,591,323 to 61,780,586
The CHD7 gene is located on the long (q) arm of chromosome 8 at position 12.2. More precisely, the CHD7 gene is located from base pair 61,591,323 to base pair 61,780,586 on chromosome 8.
C: Coloboma of the Eye
The ocular coloboma results from failure of the embryonic fissure to close along the inferonasal aspect of the optic cup and stalk between the fifth and sixth weeks of gestation. This leads to defects of the iris, ciliary body, retina, choroids, sclera and optic nerve head of the infant. The coloboma of the eye is usually asymmetrical, but it can be unilateral or bilateral....