CRYAA rs28936685: What Your Genotype Means
The rs28936685 variant is a rare genetic change located in the CRYAA gene. It is associated with the development of autosomal dominant congenital cataracts, a condition where the lens of the eye is clouded at birth.
What each genotype means
Typical Cataract Risk
You carry two copies of the standard reference allele for the CRYAA gene. This genotype is associated with normal alpha-crystallin protein structure and does not confer an elevated genetic risk for congenital cataracts. Overall risk for cataracts remains typical and influenced by standard environmental and age-related factors.
Carried by virtually 100% of individuals across all major global populations.
Congenital Cataract Predisposition
You carry one copy of the pathogenic missense variant in the CRYAA gene. In medical literature, this heterozygous change alters lens protein solubility and is strongly associated with autosomal dominant congenital or early-onset cataracts. Evidence indicates high penetrance in affected families, although clinical presentation and severity can vary.
Extremely rare globally, identified primarily in isolated families and absent or present at near-zero frequencies in population databases like gnomAD.
Severe Cataract Predisposition
You carry two copies of the pathogenic missense variant in the CRYAA gene. Because this variant acts in an autosomal dominant manner, carrying two altered copies is expected to cause severe congenital cataract development and significant lens opacity from infancy. Due to extreme rarity, homozygous clinical documentation is exceptionally limited.
Virtually non-existent in general populations, with expected frequencies far below 1 in 1,000,000.
Understanding the Variant
The variant rs28936685 is a single-nucleotide polymorphism (SNP) located within the CRYAA gene on chromosome 21. In genetic research, this specific change is often identified as a missense mutation, meaning it causes a single amino acid substitution in the resulting protein. Specifically, this change involves a transition where a guanine is replaced by an adenine, leading to an alteration in the protein structure. Because this variant is located in a highly conserved region of the gene, even small changes can have significant functional consequences for the protein's role in the eye. It is important to note that this variant is extremely rare in the general population and is typically studied in the context of specific families affected by hereditary eye conditions.
The Role of the CRYAA Gene
The CRYAA gene provides instructions for making a protein called alpha-A crystallin. This protein is a major structural component of the lens in the human eye and belongs to a family of proteins known as small heat shock proteins. Alpha-A crystallin acts as a molecular chaperone, which means it helps other proteins maintain their correct shape and prevents them from clumping together, or aggregating. By keeping lens proteins stable and soluble, alpha-A crystallin ensures that the lens remains transparent, allowing light to pass through to the retina. When the CRYAA gene is mutated, the resulting alpha-A crystallin protein may lose its ability to function properly. This can lead to the accumulation of misfolded proteins, which form opaque clusters that cloud the lens, resulting in a cataract.
Research and Evidence
Scientific research has linked the rs28936685 variant to autosomal dominant congenital cataracts. Studies have observed that this mutation co-segregates with the condition in families, meaning that individuals who inherit the variant are highly likely to develop cataracts. The evidence for this association is considered strong within the context of clinical genetics, as the mutation affects a highly conserved arginine residue, which is critical for the protein's stability and chaperone function. While the association with congenital cataracts is well-documented in specific family studies, the overall evidence strength is sometimes categorized as limited in broader genomic databases due to the rarity of the variant. Researchers continue to study how this specific amino acid change disrupts the lens environment and whether other genetic or environmental factors influence the severity of the condition.
Population Frequency
The rs28936685 variant is extremely rare globally. It is not a common polymorphism found in the general population; rather, it is typically identified through clinical investigations of families with a history of inherited eye disorders. Because of its rarity, it is not routinely screened for in standard population-wide genetic testing panels. Its presence is usually confirmed through targeted sequencing when a clinical diagnosis of congenital cataract is suspected.
What This Information Means for You
If you or a family member have been identified as having this variant, it is important to understand that this information is for educational purposes and does not constitute a medical diagnosis. Genetic variants in the CRYAA gene are complex and can manifest with varying degrees of clinical severity, even within the same family. This information should not be used to make personal health decisions or to predict specific clinical outcomes. If you have concerns about your vision or a family history of cataracts, the most appropriate step is to consult with an ophthalmologist or a genetic counselor. These professionals can provide a comprehensive eye examination, discuss the implications of your genetic status, and offer guidance on monitoring or managing your eye health based on your specific clinical presentation.
How common is this variant?
The rs28936685 variant is extremely rare globally and is not found at significant frequencies in general population databases.
Frequently asked questions
What is a congenital cataract?
A congenital cataract is a clouding of the lens of the eye that is present at birth. The lens is normally clear, but when it becomes cloudy, it can block light from reaching the retina, potentially affecting vision.
Is the rs28936685 variant common?
No, this variant is extremely rare. It is not a common genetic change found in the general population and is typically only identified in families with a history of hereditary cataracts.
Does having this variant mean I will definitely have cataracts?
While this variant is associated with autosomal dominant congenital cataracts, genetic expression can be variable. You should consult with an ophthalmologist or a genetic counselor to understand what this means for your specific health situation.
Can I fix a cataract caused by this gene?
Cataracts are typically managed by ophthalmologists through surgical procedures to replace the cloudy lens with an artificial one. Please discuss any vision concerns or treatment options with a qualified eye care professional.
Sources & further reading
Educational information only, last refreshed 10/19/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Promoter variant in CRYAA associated with age-related cataracts.
A pathogenic missense mutation in alpha-A crystallin causing autosomal dominant congenital and pediatric cataracts.
A missense mutation altering the structural chaperone function of lens alpha-crystallin, causing dominant zonular cataracts.
This variant in the alpha A-crystallin gene has been studied for its potential association with susceptibility to nuclear age-related cataracts in Han Chinese populations.