In This Article
In This Article
A cataract is a cloudy formation that appears inside the eye lens. It can range from translucent to opaque, depending on its severity.
People often associate cataracts with old age. In reality, it can affect anyone. The classifications of cataracts based on the age of onset are:
Molecular genetics identifies genes linked to inherited cataracts. Research extends to age-related cataracts, which also have genetic causes.
The list of genes associated with cataracts is far from complete. However, current research explains the link between genetic heterogeneity and cataracts.
Lens transparency depends on two components:
Old age, genetics, and environmental stress can disrupt this balance. Changes in the cells or lens proteins may result in cataract formation.
A unilateral cataract affects one eye. Meanwhile, a bilateral cataract affects both eyes.
Other names: Infantile cataracts
Congenital cataracts are present at birth or in the first year of life. In the United States, there are 1 to 6 cases of congenital cataracts in every 10,000 children. It is the leading cause of visual loss in children.
Doctors recommend getting cataract surgery months after birth. At this time, lens development is still ongoing. Early treatment prevents "lazy eye" and cataract blindness.
Congenital cataracts have several classifications:
Other names: Inherited congenital cataract
Inherited cataracts account for 8.3 to 25 percent of all congenital cataracts. About 70 percent of cases are isolated cataracts. Thirty percent of inherited cataracts occur with other eye disorders or diseases.
Most inherited congenital cataracts are due to eye lens mutations. They usually result in bilateral congenital cataracts. However, some only develop unilateral congenital cataracts.
The two main classifications of inherited cataracts are:
Congenital cataracts are passed through non-sex chromosomes called autosomes. Thus, a child’s sex doesn’t affect their risk for an inherited cataract.
Other names: Autosomal dominant inherited cataracts
An autosomal dominant cataract is a type of inherited congenital cataract. It has an autosomal dominant pattern, so a single copy of a mutated gene is enough to cause cataracts.
Below are some autosomal dominant congenital cataracts:
Other names: Autosomal recessive inherited cataracts
An autosomal recessive cataract is another type of inherited cataract. It has an autosomal recessive pattern, requiring two copies of a mutated gene to cause cataracts. Most of these cataracts occur with other diseases. However, many types (such as nuclear cataract) occur alone.
Some diseases that cause autosomal recessive cataract are:
A baby can develop cataracts before birth. Risk factors include:
An isolated cataract occurs alone. Hence, the genetic mutation only affects the eye lens. Posterior polar cataract and anterior polar cataract are types of isolated cataracts.
Complex congenital cataracts affect different parts of the eye structure. They are often accompanied by ocular abnormalities such as:
Lamellar cataracts linked to the MIP gene are examples of complex cataracts. They cause opacities in the lamellar, sutural, polar, and cortical parts of the eye.
Congenital cataracts may arise as a symptom of metabolic or genetic disease. Lowe syndrome and type 2 neurofibromatosis are some illnesses that cause congenital cataracts.
Other names: Childhood cataract, juvenile cataract
Pediatric cataract is the leading cause of visual impairment in older children. It requires early treatment and long-term management. Otherwise, it can lead to lifelong blindness.
Known causes of pediatric cataracts include:
About half of childhood cataracts are hereditary. As a type of inherited cataract, it is caused by mutations that disrupt the lens cell homeostasis. Unlike congenital cataracts which appear at birth, they occur at a later age.
Most mutations occur as autosomal dominant cataracts, such as:
But they can also occur as autosomal recessive cataracts like:
Acquired cataracts develop after exposure to external factors. Eye trauma is the leading cause of childhood cataracts, especially in boys. Metabolic and systemic disorders may also cause cataract formation. Examples include myotonic dystrophy and Warburg micro syndrome.
Pre-senile cataracts have an early onset of 18 to 45 years old. Genetics and external factors both play a role in their development. Posterior subcapsular cataract commonly affects this age group. It is a type of autosomal dominant cataract.
Other risk factors for pre-senile cataracts are:
These external factors can directly cause pre-senile cataracts. Alternatively, they can worsen pre-existing inherited cataracts.
Age-related cataracts appear after the age of 45. Cumulative damage to lens proteins is a common cause. Genetic mutations, which interfere with lens cell homeostasis, may also cause age-related cataracts.
Structural proteins called crystallins make up the eye lens. There are three main kinds of lens crystallins:
Aging causes betagamma-crystallins to “denature” or lose their structure. Rather than rebuild them, alpha-crystallins release them to the cytoplasm.
Denatured crystallins build up over time and form a complex. Alpha-crystallins eventually become overwhelmed. Betagamma-crystallins then form into an insoluble protein, which is the cataract.
Cataracts can lead to visual impairment and blindness. Early diagnosis and treatment are vital in preventing them. Genetics are a major cause of cataracts across all age groups. With DNA testing, you can check if you’re at risk for cataract formation.
A complete health report will also assess your risk for genetic conditions like:
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