Primary Congenital Glaucoma

Primary congenital glaucoma (PCG) is an inherited disorder that affects the eyes, usually caused by increased blood pressure within the eye, causing damage to the optic nerve which is responsible for communication between the eye and the brain. It is typically diagnosed in the first year of life. Additional symptoms include discomfort with bright light, clouding of the cornea and babies who tear up easily and often. Only one eye may be affected, but in about half individuals with PCG, both eyes are affected. Early diagnosis and appropriate treatment of PCG can improve visual outcome. Depending on when the condition is treated, the clarity and sharpness of vision may be reduced and/or visual fields may be restricted. If the condition is not treated, blindness invariably occurs. Affected individuals are developmentally and cognitively normal. The life expectancy and intellect of individuals with PCG caused by CYP1B1 pathogenic variant are not affected. One of the causes of PCG is pathogenic variants in the CYP1B1 gene.

PCG is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

There are generally no signs or symptoms associated with being a carrier for PCG. The risk for a carrier to have a child affected with PCG is increased. Testing of reproductive partners is recommended for carriers of PCG.

Primary congenital glaucoma affects all ethnicities throughout the world, but the birth occurence varies worldwide. In western countries, it affects 1 in 5,000-22,000 newborns, 1 in 2,500 in the Middle East, 1 in 1,250 in the Romani population of Slovakia, and 1 in 3,300 in the Indian state of Andhra Pradesh. Primary congenital glaucoma is the most common cause of childhood blindness in Saudi Arabia and in the Romani population of Slovakia.

Genetics Home Reference: Early-onset glaucoma (http://ghr.nlm.nih.gov/)

OMIM [GLAUCOMA 3, PRIMARY CONGENITAL, A; GLC3A: 231300] (http://www.ncbi.nlm.nih.gov/omim)
Gene Reviews: Primary Congenital Glaucoma (http://www.ncbi.nlm.nih.gov/books/NBK1116/)

• Full gene sequencing