Early onset glaucoma (Early-onset glaucoma) - Genes MYOC and CYP1B1.
Glaucoma is a group of eye conditions in which the optic nerves that connect the eyes and brain progressively damaged. This damage can lead to reduced peripheral vision and eventually blindness. Other signs and symptoms may include profusion eye, excessive tearing and photophobia. The term "early - onset glaucoma" can be used when the alteration occurs before 40 years. In most people with glaucoma, damage to the optic nerves it is due to intraocular pressure.
Usually, glaucoma develops in older adults, in whom the risk of developing the disorder may be influenced by a variety of medical problems such as hypertension and diabetes mellitus and family history. The risk of early - onset glaucoma depends mainly on heredity. Structural abnormalities that prevent drainage of fluid in the eye may be present at birth and often are apparent during the first year of life. If glaucoma occurs before 5 years, with no other associated abnormalities, called primary congenital glaucoma. Other individuals have early onset primary open - angle glaucoma, the most common adult form of glaucoma. If the primary open - angle glaucoma develops during childhood or young adulthood, it is called open - angle glaucoma youth.
Early - onset glaucoma is due to mutations in the CYP1B1 genes and MYOC. Individuals with mutations in both genes may develop glaucoma at an earlier than those with mutations in only one of the genes age.
The MYOC gene, located on the long arm of chromosome 1 (1q23 - P24), encoding the protein myocilin. This protein is localized in the trabecular meshwork and ciliary body, which regulate intraocular pressure and various types of muscle. It is believed that protein helps to control intraocular pressure through its action in muscle tissue of the ciliary body. They have identified more than 40 mutations in the gene MYOC, causing disease. Mutations in the gene can alter the myocilin protein so that its interaction with other proteins is hampered. A defective protein which is not incorporated into protein complexes can accumulate in the ciliary body and the trabecular meshwork. This prevents excess protein sufficient fluid flow from the eye, resulting in an increase in intraocular pressure, causing the signs and symptoms of the disease.
The CYP1B1 gene, located on the short arm of chromosome 2 (2p22.2), encoding an enzyme family member cytochrome P450 enzyme. These enzymes are involved in many processes in the body, such as help with drug reactions that break down and produce lipids. CYP1B1 enzyme participates in biochemical reactions in which an oxygen atom is added to other molecules. This enzyme is active in many tissues, including the eye structures. Although it is unclear l enzyme function in eye development, it is believed to play a role in the formation of structures in the front of the eye and in a process that regulates the secretion of fluid within it. There are more than 140 mutations in the CYP1B1 gene cause early - onset glaucoma. Mutations result in an unstable or a incorrectly enzyme. Although No well it understood how defects in the enzyme leading to the signs and symptoms of the disease, it is believed that such defects can interfere with the early development of the trabecular meshwork. If the fluid can not drain, you can increase the pressure within the eye, which is characteristic of glaucoma. CYP1B1 enzyme can interact with the myocilin protein encoded from MYOC gene. Individuals with mutations in both genes can develop glaucoma at a younger age and have more severe than those with mutations in only one of the genes symptoms.
Early onset glaucoma can have different patterns of inheritance. Primary congenital glaucoma generally inherited in an autosomal recessive pattern, which means that both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease. Meanwhile, juvenile glaucoma open angle is inherited in an autosomal dominant, which means that a copy of the altered gene in each cell is sufficient to cause disease. In some families, the primary congenital glaucoma can also be inherited in an autosomal dominant pattern.
Tests in IVAMI: in IVAMI perform detection of mutations associated with early - onset glaucoma, by complete PCR amplification of the exons of the MYOC and CYP1B1 genes, respectively, and subsequent sequencing.
Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).