PAX6 rs121908870: Understanding This Rare Genetic Variant
The rs121908870 variant is a rare genetic alteration located within the PAX6 gene. It is associated with significant disruptions to eye development, specifically conditions like congenital aniridia and anterior segment dysgenesis.
What each genotype means
Typical PAX6 function
This genotype represents the common, non-variant sequence for this location in the PAX6 gene. Individuals with this genotype do not carry the specific high-penetrance substitution associated with congenital aniridia at this site.
This is the most common genotype observed in the general population.
High-penetrance aniridia risk
This genotype indicates the presence of a single copy of the c.286G>T (p.Glu96Ter) variant, which introduces a premature stop codon in the PAX6 protein. This is a high-penetrance mutation associated with congenital aniridia and related anterior segment dysgenesis, typically inherited in an autosomal dominant manner.
This genotype is extremely rare and is observed almost exclusively in affected clinical lineages.
Severe PAX6-related disorder
This genotype indicates the presence of two copies of the c.286G>T variant. While most clinical reports focus on heterozygous carriers, homozygous or compound heterozygous mutations in PAX6 are generally associated with severe, often lethal, developmental phenotypes in early life.
This genotype is exceptionally rare and has not been widely documented in general population databases.
What is the rs121908870 Variant?
The rs121908870 variant is a specific single nucleotide substitution located within the PAX6 gene, which is situated on chromosome 11. In genetics, a single nucleotide polymorphism (SNP) or variant represents a change in one of the chemical building blocks of DNA. This particular variant is classified as a high-penetrance change, meaning that individuals who carry this specific alteration are highly likely to exhibit the associated clinical features. Because it disrupts the normal sequence of the gene, it can interfere with the production of the PAX6 protein, which is essential for the proper formation of various tissues during embryonic development. This variant is not a common feature of the human genome but is instead identified primarily in clinical settings where individuals present with specific congenital ocular conditions.
The Role of the PAX6 Gene
The PAX6 gene acts as a master regulator, often described as a transcription factor, which means it provides instructions for making a protein that binds to DNA to control the activity of other genes. This protein is critical during the early stages of development, particularly for the eyes, brain, and spinal cord. Because PAX6 is so sensitive to the amount of protein produced, even small changes in its sequence or expression levels can have profound effects on ocular morphogenesis. When the PAX6 protein is absent or dysfunctional, the development of the iris, lens, and cornea can be severely impacted. This is why mutations in this gene are frequently linked to complex developmental eye disorders, including aniridia, where the iris is partially or completely missing, and other forms of anterior segment dysgenesis.
Research and Clinical Associations
Research into rs121908870 and other PAX6 variants is primarily conducted through clinical studies of families affected by congenital eye disorders. The evidence linking this specific variant to disease is strong in the context of clinical genetics, as it is identified in individuals presenting with clear phenotypic traits of aniridia. However, it is important to note that the overall evidence strength for many rare variants remains limited to specific affected lineages rather than broad population-wide studies. Scientists use these findings to better understand how the PAX6 protein functions and how its disruption leads to specific clinical outcomes. While the association with ocular development is well-documented, the severity of the condition can vary even among individuals with the same variant, suggesting that other genetic or environmental factors may also play a role in the final clinical presentation.
Population Frequency and Interpretation
The rs121908870 variant is extremely rare in the general population. It is not a common variation found in healthy individuals; rather, it is observed almost exclusively within families or lineages that have a history of congenital aniridia or related anterior segment dysgenesis. Because it is so rare, it does not appear in standard frequency tables for the general public. For a reader, this information is primarily relevant in a clinical diagnostic context. If this variant is identified in a medical report, it is typically part of a diagnostic process for an existing condition. It is not a predictive marker for the general population. If you or a family member have concerns about genetic eye conditions, it is essential to consult with a clinical geneticist or an ophthalmologist who can provide context based on your specific medical history and family background.
How common is this variant?
This variant is extremely rare and is observed almost exclusively in affected lineages rather than the general population.
Frequently asked questions
What is aniridia?
Aniridia is a congenital condition characterized by the partial or complete absence of the iris, the colored part of the eye. It is often associated with other vision problems and is frequently caused by mutations in the PAX6 gene.
Is rs121908870 common?
No, this variant is extremely rare. It is not found in the general population and is typically only identified in individuals or families with specific congenital eye conditions.
Can I use this information to diagnose myself?
No. Genetic information should never be used for self-diagnosis. If you have concerns about your vision or family history, you should consult a medical professional or a genetic counselor.
What should I do if I have this variant?
If this variant has been identified in a clinical report, you should discuss the findings with your healthcare provider or a genetic counselor. They can help you understand what this means for your health and provide appropriate guidance.
Sources & further reading
Educational information only, last refreshed 10/14/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Pathogenic loss-of-function nonsense variant in PAX6 resulting in congenital absence of the iris (aniridia) and associated anterior segment dysgenesis.
Nonsense change in PAX6 leading to haploinsufficiency and classical congenital aniridia.
A classic nonsense mutation (p.Arg240Ter) in the PAX6 master regulator of eye development leading to haploinsufficiency and congenital aniridia.
Intronic regulatory polymorphism in the ocular master regulator PAX6 associated with axial length variation and myopia development.
Classical stop-gain variant in PAX6 leading to haploinsufficiency and congenital aniridia with associated foveal hypoplasia and decreased visual acuity.
Pathogenic missense variant in PAX6 causing developmental ocular malformations including aniridia and congenital ocular coloboma.