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Name: Mona
Status: student
Grade: 9-12
Location: Outside U.S.
Country: USA
Date: Winter 2012-2013


Question:
Why is the disease glaucoma more found in old people? It is genetic so it is found in children too.



Replies:
Hi Mona,

Generally we think of glaucoma as a disease or physical condition of ageing. Essentially UV light over time causes the lens of the eye to get clouded. The lens is made of protein and water. Proteins absorb UV light and over time get opaque from the UV light croslinking the proteins. This not a genetic issue although it may have some small genetic link. This is difficult to define since often the environmental factors of parents and children are similar.

There exists a genetic form. I have abstracted a very good explanation from a web site that explains it better than I can. Here is the complete link and some info. I suggest you look at the entire article.

"The pediatric glaucomas that are inherited include congenital, infantile and juvenile glaucoma as well as some glaucoma associated with abnormalities in the structure of the eye such as aniridia and Axenfeld-Reiger syndrome. These genetic forms of glaucoma are thought to arise from gene errors called mutations. These are errors in the hereditary material (DNA), which is inherited from our parents. If you think of a gene as a recipe to make something, a mutation is like missing one of the ingredients or one ingredient replaced by a different ingredient. When a gene is not normal, then the gene's instructions are not normal and this often leads to a disease, in this case, glaucoma. A mutation in a pediatric glaucoma gene may be inherited in a family or it may just start for the first time in a child who is the first in their family to have the glaucoma. The people "carrying" or having this defect may pass the mutation on to their children allowing the glaucoma gene to be passed from one generation in a family to the next.

Glaucoma may be inherited in different ways, either autosomal dominant (AD) or autosomal recessive (AR). The risk of transmitting the disease to future generations is very different, ranging from close to zero to 50%. When only one person in the family is known to have pediatric glaucoma, it is difficult to know what type they have. For brothers and sisters of a newly diagnosed first child with no other affected family member, the risk we use is 8% for the second child born to be affected. This is an average risk, combining dominant and recessive risks. But if it is known that the glaucoma in the family is autosomal dominant, than the risk of an affected person having an affected child is 50% for each pregnancy. If the form is autosomal recessive, then the risk is less than 3% because the affected person would have to marry a carrier (very unlikely unless they marry a relative or someone from a very tightly knit ethnic group) to have an affected child.

Since it is known that glaucoma can be passed from both parents (AR) or one parent (AD) to their children, the appropriate standard of care is to periodically examine all brothers, sisters, sons and daughters at risk starting at or near birth."

Stephen R. Dunn
Ass't Professor of Medicine (ret.)
Dept. Medicine/ Div. Nephrology


Hi Mona,

Thanks for the question. I am not sure why glaucoma is more common in older people. Have you searched the internet on this topic? I am curious to know what you have come across.

Yes, there is definitely a genetic component to glaucoma as it runs in my family.

I hope this helps you. Please let me know if you have any more questions.

Thanks
Jeff



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