Have You Got the Gene for Glaucoma?

Family History of Glaucoma is Dangerous

​While everyone is at risk for glaucoma, certain groups of people are at an increased risk than certain others. Glaucoma is the name used for a group of diseases that irreversibly damage the optic nerve resulting in decreased eyesight and finally total blindness, if left untreated. There are no early symptoms or pain in most people and it is advisable for people in the high-risk category to get their eyes tested every year. High-risk category includes those above the age of 40 and those having a family history of the disease. Individuals having diabetes or at risk for other eye diseases should also get their eyes checked regularly.

Generally, glaucoma affects older adults but risks of early-onset glaucoma depends on heredity. Structural abnormalities that affect fluid drainage in the eye may be present at birth and becomes prominent during the first year of life. These abnormalities are usually a part of a genetic disorder that can affect many body systems and is called a syndrome.

Recently, people have gained more clarity on the genetic cause of glaucoma.

Primary Open-angle Glaucoma (POAG)
This is the most common form of glaucoma affecting almost 33 million people worldwide. No obvious abnormality in the eye can be blamed for this and mutations in several genes such as myocilin, optineurin and CYP1B1 are termed to be the causing agents, responsible for less than 10% of the cases worldwide. Large-scale genetic studies done using the blood samples of thousands of glaucoma patients have led to the discovery of more common genetic factors for POAG. Some of these factors include a change in the DNA sequence or actual loss of DNA.

Primary congenital Glaucoma (PCG)
This is the most common form of glaucoma that affects young children, right from birth up to 3 years of age, and leads to blindness in these kids. It affects almost 80% of infants within the first year of birth. Around 60-80 percent of cases are bilateral and it affects males more frequently (65%) than females (35%). Mutations in the CYP1B1 gene is the major cause of PCG worldwide.

Primary Angle-closure Glaucoma (PACG)
This is the second-most common form of glaucoma affecting around 16 million people worldwide. Here, the drainage angle closes over time blocking the pathway to the drainage system leading to increased eye pressure. Research has also found genetic variants associated with this form of glaucoma and it is still under study.

Exfoliation Glaucoma (XFG)
Also called as the pseudoexfoliation glaucoma, it affects millions of people around the world and is the most common form of OAG globally. XFG is inherited as a complex and late-onset disorder dominant more among the female and the aged population. XFG is associated with 20% to 60% of OAG in many countries around the world and is one of the leading causes of ocular morbidity.

XFG is a result of exfoliation syndrome, a condition where white protein-like material is formed on the lens and within the fluid drainage system of the eye and in tissues all over the body. Genetic variants are associated with XFG and research is underway on the association of these variants with protein deposits and their role in glaucoma.
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Although these genetic discoveries are mind blowing, they are still under research and not in a stage where they can be practically used. We are still not aware how these gene abnormalities can cause glaucoma, but hopeful of a stage where treatment can be developed for every type of glaucoma cause due to gene abnormalities. As glaucoma is a polygenic condition, specific gene therapies for individual mutations is not practical but therapies to cure common pathways that lead to glaucoma is feasible. For more information on gene-related diseases, please visit the website www.firsteatright.com.