Is Glaucoma Hereditary? How To Identify Your Risk?

Glaucoma can be a silent cause of vision problems, affecting millions of Americans every year.

Since there are no significant early symptoms, people don’t get their eyes tested until very late.

Genetic mutations are one of the most common causes of developing glaucoma, and getting yourself genetically tested may help diagnose and treat this condition early on.

Genetic testing and regular eye testing are especially recommended for people who have first-degree relatives with glaucoma.

Read more about glaucoma, its risk factors, causes, and preventive methods here.

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Introduction

Glaucoma affects 3 million Americans annually and is the second most common cause of blindness worldwide.

With no clear early signs, most people don’t know they have glaucoma until they start losing vision.

This condition causes damage to the optic nerves and can be inherited.

Genetic testing may help you understand if glaucoma is hereditary and know your risk for developing this condition.

Individuals with a genetic predisposition for glaucoma may need regular eye exams to monitor intraocular pressure (IOP) and optic nerve health.

What Is Glaucoma?

Glaucoma is a group of eye conditions that cause damage to the optic nerves.

The optic nerves are responsible for sending visual signals from the eye to the brain and help visualize.

Glaucoma is a progressive disease, which means that the symptoms progress slowly.

Types Of Glaucoma

There are four common types of glaucoma diagnosed.

Open-Angle Glaucoma

Open-angle glaucoma (OAG) is one of the common forms of glaucoma caused by increased intraocular pressure (eye pressure).

This is also called primary open-angle glaucoma (POAG).

OAG is a progressive condition, with eye pressure increasing slowly. Increased eye pressure puts pressure on the optic nerves and damages them over time.

Primary open-angle glaucoma is hereditary and can be genetically acquired.

Angle-Closure Glaucoma

This form of glaucoma occurs due to a sudden increase in eye pressure.

Aqueous humor is a fluid produced in the eye for lubrication.

This clear liquid maintains eye pressure.

In people with angle-closure glaucoma, the movement of the fluid is blocked; the liquid is unable to circulate inside the eye.

As a result, the eye pressure suddenly increases, causing damage to the optic nerves.

A sudden blurred vision or an inability to see should be considered a medical emergency.

In most cases, angle-closure glaucoma in one eye can also put the person at risk for glaucoma in the second eye. Getting help right away can save the other eye.

Normal-Tension Glaucoma

Generally, one of the common causes of glaucoma is increased intraocular pressure (IOP).

However, in the case of normal-tension glaucoma, the optic nerve gets damaged even though the IOP stays normal.

Normal-tension glaucoma could be an inherited condition or a result of low blood flow to the optic nerves.

Early-onset Glaucoma

Early-onset glaucoma is a type diagnosed before the age of 40 in adults.

This type is primarily hereditary and may occur even without related risk factors.

A majority of cases of early-onset glaucoma are of primary open-angle glaucoma type.

Juvenile Open-angle Glaucoma

When open-angle glaucoma is diagnosed in early childhood or early adulthood, it is called juvenile open-angle glaucoma.

Congenital Glaucoma

Congenital glaucoma is the development of glaucoma in children before the age of three.

This birth condition leads to optic nerve damage and vision loss in babies.

Congenital glaucoma could be hereditary or due to birth complications affecting the baby’s eye as a fetus.

Secondary Glaucoma

Secondary glaucoma is the development of either open-angle or angle-closure glaucoma due to another condition.

Some causes that could lead to secondary glaucoma are:

Health conditions like diabetes or hypertension
Eye diseases or infections
Injury to the eye
Use of certain medicines that can increase eye pressure

How’s Glaucoma Caused?

One of the major causes of glaucoma is high eye pressure. The eye keeps making this clear fluid called aqueous humor used in lubricating the eyes.

The fluid flows around the eyes and gets drained out. When new liquid circulates, the same amount should be drained to stabilize the eye pressure.

The drainage happens through the drainage system.

If the drainage angle is blocked, this causes fluid build-up, leading to high eye pressure.

This increased eye pressure pressurizes the optic nerves.

Over time, the nerve fibers of the optic nerves may die, causing problems like blind spots and side vision.

Symptoms of Glaucoma

Symptoms Of Open-angle Glaucoma

Open-angle glaucoma may not show early signs.
Advances symptoms include blurred vision, loss of side (peripheral) vision, and gradual loss of central vision.

Symptoms Of Angle-closure Glaucoma

Headaches
Nausea and vomiting
Blurred vision
Halos around light sources
Eye pain

Infographic showing the different types of glaucoma

Symptoms Of Congenital Glaucoma

Cloudy eyes
Increased blinking
The flow of tears from eyes without crying
Red eyes
Sensitivity to light

Symptoms Of Secondary Glaucoma

The symptoms would depend on whether the person develops open-angle or angle-closure glaucomas.

Risk Factors For Glaucoma

The following are risk factors for glaucoma.

The risk of glaucoma increases with age. According to the Centers for Disease Control and Prevention (CDC), people above 40 years should get an annual eye checkup done to check for glaucoma.

Family History

According to studies, about 50% of all cases of Open-Angle Glaucoma (OAG) have a positive family history of glaucoma associated.

The risk of developing OAG increases 9-folds when first-degree relatives have the condition.

A study reports that glaucoma was diagnosed in 10.4% of siblings of glaucoma patients. Without a sibling affected, the average risk of developing glaucoma was only 0.7%.

Race

African Americans seem to have a higher risk of developing OAG when compared to people of other races.

A 2017 study reports that the prevalence of OAG is 3.4% in African Americans, 1.7% in Caucasians, and 1.5% in Hispanics.

The same study concludes that African Americans have higher eye pressure levels, increasing their risk of blindness due to primary OAG.

Myopia

Myopia (nearsightedness) is a condition affecting about 41.6% of Americans.

The risk of developing glaucoma and the intensity of progression may depend on the degree of myopia.

Hypotension And Hypertension

Hypotension (low blood pressure) and hypertension (high blood pressure) are both risk factors for developing glaucoma.

Diabetes

A 2014 meta-analysis reports that people with diabetes mellitus are more likely to develop Primary OAG (POAG).

Is Glaucoma Hereditary?

Some forms of glaucoma may be hereditary and passed on through the family.

Early-onset Glaucoma

Early-onset glaucoma is hereditary and caused by certain gene variations passed on through the family.

Primary Congenital Glaucoma

Primary congenital glaucoma is hereditary and diagnosed before the age of three.

According to studies, variations in the CYP1B1 or LTBP2 genes may lead to the development of primary congenital glaucoma.

Primary Open-angle Glaucoma

Primary open-angle glaucoma (POAG) is another type that could be inherited.

A 2011 study reports that single-gene mutations cause 5% of all POAG.

A combination of multiple gene changes and environmental risk factors causes most other cases.

For instance, juvenile open-angle glaucoma, a condition that leads to glaucoma in young adults, may be caused by changes in the MYOC gene.

Is Glaucoma Inherited From The Father?

Glaucoma is hereditary and is inherited from both parents.

If both parents carry mutated genes and pass this on to the child, the child may receive two copies of the mutation, leading to the development of the condition.

Does Glaucoma Always Run In Families?

Some variants of glaucoma may run in the family. The parents may be carriers of the mutated genes and not develop the condition themselves.

In other cases, risk factors like hypertension, hypotension, diabetes, age, or eye injury may all lead to the development of glaucoma.

What Gender Is Most Likely To Get Glaucoma?

A meta-analysis analyzed gender-based risk factors for developing OAG in 46 published observational studies.

According to the study, men are more likely to develop glaucoma than women.

Genes Underlying Glaucoma

There are several gene mutations associated with glaucoma in human beings.

MYOC Gene Mutations

The myocilin (MYOC) gene is responsible for producing the myocilin protein.

This protein is essential in maintaining intraocular pressure in the eyes.

Variations in the MYOC gene may lead to underproduction of the myocilin protein, leading to increased intraocular pressure and glaucoma.

There are more than 100 variations of the MYOC gene identified to date.

About 4% of all cases of POAG and more than 10% of all cases of JOAG are due to MYOC mutations.

CYP1B1 Gene Mutations

The Cytochrome P450 family 1 subfamily B member 1 (CYP1B1) gene produces the CYP1B1 enzyme.

There are more than 100 variations of this gene identified.

Mutations in the CYP1B1 gene at the GLC3A locus are responsible for 50% of all cases of Primary Congenital Glaucoma (PCG).

LTBP2 Gene Mutations

The Latent Transforming Growth Factor Beta Binding Protein 2 (LTBP2) gene produces the LTBP2 protein.

This protein is necessary for forming the anterior chambers of the eye.

A 2009 study reports that null mutations in the LTBP2 gene may be associated with an increased risk of developing PCG.

Mutations in the following genes may also lead to glaucoma.

OPTN
TBK1
ABCA1
AFAP1
GMDS
PMM2
TGFBR3
FNDC3B
ARHGEF12
GAS7
FOXC1
ATXN2
TXNRD2
EPDR1
CHAT
GLIS3
FERMT2
DPM2-FAM102

Identifying Your Genetic Risk For Glaucoma

If you have first-degree relatives with glaucoma, it will help to get your genes tested to understand your risk.

According to the National Eye Institute, everyone with first-degree relatives with glaucoma should get a comprehensive eye exam once in two years to analyze their risk.

Genetic testing is beneficial in identifying early-onset glaucoma, a condition that causes glaucoma in young adults under 40 years of age.

If genetic testing reveals a higher risk for developing glaucoma, you may need to get regular eye exams done by an eye doctor to diagnose the condition before it worsens.

Summary

Glaucoma is a group of conditions that damage the eye's optic nerves, leading to vision problems and blindness.
Primary Open-angle Glaucoma (POAG), Angle-closure Glaucoma, Normal-tension Glaucoma, Early-onset Glaucoma, Juvenile Open-angle Glaucoma, Congenital Glaucoma, and Secondary Glaucoma are different types of the condition.
Glaucoma is primarily the result of high eye pressure or intraocular pressure. Increased pressure in the eyes affects the optic nerves, leading to their damage.
Individuals with glaucoma may not notice any early symptoms. Over time, glaucoma can cause loss of peripheral vision and central vision, headaches, and gradual loss of sight.
Some risk factors for glaucoma are age, family history, hypertension, hypotension, diabetes, and myopia.
Many types of glaucoma could be hereditary and passed on through the family.
Multiple gene changes could increase a person’s risk of developing glaucoma. Gene mutations and environmental factors decide when a person develops the condition and its progress.
Genetic testing can help know if an individual is at high risk for developing glaucoma. High-risk individuals would benefit from getting their eyes tested regularly to identify symptoms of glaucoma and treating them early on.