Most common forms of strabismus tend to run in families. But the genetics of strabismus are complex, so it’s not always simple to predict whether a child will inherit the condition.
Strabismus is a common eye condition usually diagnosed in early childhood. In strabismus, one or both of your eyes appear misaligned or crossed.
There are many types of strabismus. The condition can:
- present in infancy or develop over time
- be constant or infrequent
- affect one eye or both eyes
Strabismus tends to run in families. Talk with your child’s doctor if you have a family history of strabismus. The doctor will ensure that your child is monitored appropriately.
Typical eye alignment requires precise coordination of your brain and nerves, the muscles controlling your eye movements, and your eyeball itself. Strabismus can be due to problems in any of these areas.
Some causes of strabismus, such as those related to muscles or nerves, are present from birth. Others can develop over time.
Genetics play a role in strabismus. If your parent or sibling has strabismus, you have a greater chance of developing it as well.
Other risk factors for common childhood strabismus include:
- certain eye conditions, such as:
- medical conditions like cerebral palsy and epilepsy
- low birth weight (less than
2,000 grams, or about 4 pounds 6 ounces)
- older age of the birthing parent
- smoking during pregnancy
Some rare forms of strabismus are due to a mutation (change) in a single gene. Some of these mutations are dominant, meaning you need only one copy of the mutated gene (from one parent) to inherit the condition. Others are recessive, meaning you need two copies of the mutated gene (one from each parent) to inherit it.
But for most common forms of childhood strabismus, inheritance is more complex. Research has identified several genes that can contribute. Interaction among genes and the environment most likely causes childhood strabismus.
Twin and sibling studies help show how genetics can play a large (but not exclusive) role in strabismus. In studies of identical twins where one twin has common childhood strabismus, the other twin has up to an 82% chance of developing strabismus. In twins who are not identical, the chance is only as high as 47%.
Does strabismus run in families?
Yes, strabismus tends to run in families. A 2023 study found that
Some types of strabismus may be more likely to run in families. In the same study, people with esotropia (eyes drifting inward toward their nose) were more likely to have a family history than people with exotropia (eyes drifting outward).
How strabismus is inherited may depend on whether it’s concomitant or incomitant. “Concomitant” means the deviation of your eyes doesn’t change depending on the direction of your gaze. “Incomitant” means the direction of your gaze can affect the deviation.
Most common forms of concomitant childhood strabismus tend to run in families, but inheritance is not clearly dominant or recessive. It’s more complex. This is likely because these forms of strabismus are due to many combinations of genetic and environmental risk factors.
In rare types of incomitant strabismus, inheritance may be clearer. For example, Duane syndrome can be inherited in an autosomal dominant pattern. There are also rare forms of strabismus that show a recessive pattern.
Research has linked common forms of childhood strabismus to several genetic mutations, including in multiple genes on chromosomes 4 and 7. One 2018 study of family groups with strabismus also found mutations on chromosomes 1 and 21.
But inheritance of common childhood strabismus is often complex. Researchers continue to search for genes that cause strabismus.
How common is strabismus?
Overall, strabismus is quite common. It affects 2–4% of children.
Is strabismus inherited from the mother or the father?
Common types of childhood strabismus can be inherited through the mother, the father, or both. This strabismus likely develops from a combination of genetic and environmental interactions.
For example, a 2018 study identified a genetic mutation (WRB on chromosome 21) that is more likely to pass through the father’s line.
What are the odds of a parent passing strabismus on to their child?
In general, when one parent has common childhood strabismus, their child is 3–5 times more likely to develop it than the larger population.
Rarely, the odds may be more clearly defined, such as when a parent has an identifiable dominant or recessive form of strabismus.
Your child’s doctor will help you understand risk and guide age-appropriate monitoring and screenings.
Is amblyopia genetic?
Amblyopia (“lazy eye”) is a loss of vision, usually in one eye. Strabismus is one possible cause of amblyopia, but there are other causes.
Amblyopia is not a genetic condition, but some factors that contribute to it (such as strabismus) may be genetic.
Strabismus is a common eye condition that causes eye crossing or misalignment. There are many types of strabismus.
This condition tends to run in families, but inheritance of most childhood strabismus is not clearly predictable. Research is ongoing but has identified several genetic and environmental risk factors.
Early detection of strabismus is important. Treatment can help ensure healthy development of vision and prevent future complications.
Let a doctor know if you suspect that your child may have strabismus, if you have strabismus, or if strabismus runs in your family. Your doctor can guide you in screening for and managing the condition.