RHO rs121912526: Understanding This Rare Genetic Variant
The rs121912526 variant is a rare genetic change in the RHO gene that results in a constitutively active rhodopsin protein. This specific alteration is associated with autosomal dominant congenital stationary night blindness (CSNB).
What each genotype means
Typical rhodopsin function
This genotype represents the common, non-variant form of the RHO gene at this position. Individuals with this genotype do not carry the specific Gly90Asp mutation associated with autosomal dominant congenital stationary night blindness.
This is the most common genotype found in the general population.
Associated with night blindness
This genotype indicates the presence of one copy of the Gly90Asp (G90D) variant. This specific variant is known to cause constitutively active rhodopsin, which is linked to autosomal dominant congenital stationary night blindness. Please discuss these findings with a medical professional or genetic counselor to understand the clinical implications for your health.
This genotype is extremely rare in the general population.
Associated with night blindness
This genotype indicates the presence of two copies of the Gly90Asp (G90D) variant. This variant is associated with autosomal dominant congenital stationary night blindness, a condition characterized by stable vision loss in low-light environments. Please consult with a healthcare provider or genetic specialist to discuss the significance of this result.
This genotype is extremely rare in the general population.
What is the rs121912526 Variant?
The rs121912526 variant is a specific change in the DNA sequence of the RHO gene, which encodes the protein rhodopsin. In this variant, a single nucleotide change leads to an amino acid substitution known as Gly90Asp. This means that at position 90 of the rhodopsin protein, the amino acid glycine is replaced by aspartic acid. This specific change is classified as a constitutively active mutation, meaning the protein remains in an 'active' state even without the presence of light, which is its normal trigger. Because this variant is located in a gene critical for vision, it has been identified in clinical research as a cause of specific inherited retinal conditions. It is important to note that this variant is extremely rare in the general population, and its presence is typically identified through specialized genetic testing in individuals or families experiencing symptoms of night blindness.
The Role of the RHO Gene
The RHO gene provides instructions for making a protein called rhodopsin, which is found in the rod cells of the retina. Rod cells are the photoreceptor cells in the eye that are highly sensitive to light and are essential for vision in low-light conditions, such as at night. Rhodopsin acts as a light-sensitive pigment; when light hits the retina, it triggers a chemical change in rhodopsin that sends a signal to the brain, allowing us to see. Because the RHO gene is so vital for the proper function of these light-detecting cells, any significant change to its structure can disrupt the normal visual cycle. While many RHO variants are well-known for causing progressive conditions like retinitis pigmentosa, others, like rs121912526, are specifically linked to congenital stationary night blindness, a condition where the ability to see in the dark is impaired from birth but does not typically worsen over time.
Research and Clinical Evidence
Research into the rs121912526 variant is grounded in clinical observations of families affected by congenital stationary night blindness. Scientific literature identifies this variant as a cause of the autosomal dominant form of the condition, meaning that inheriting a single copy of the altered gene from one parent is sufficient to manifest the trait. The evidence for this association is considered strong within the context of clinical genetics, as the Gly90Asp substitution has been documented to alter the biochemical properties of the rhodopsin protein. However, because the variant is extremely rare, large-scale population studies are limited. Most of our understanding comes from case reports and family studies rather than broad population-wide screenings. As with many rare genetic variants, the clinical expression can be variable, and researchers continue to study how such mutations impact the long-term health of the retina compared to other, more common RHO mutations.
Population Frequency and Interpretation
The rs121912526 variant is classified as extremely rare across all major human populations. It is not a common polymorphism found in the general public, and it is not typically included in standard wellness-focused genetic panels. Because of its rarity, there is no significant data regarding its frequency across different ancestral groups. If an individual is found to carry this variant, it is usually in the context of a diagnostic investigation for unexplained vision issues. It is important to understand that having a rare variant does not automatically guarantee a specific clinical outcome, as genetic background and environmental factors can influence how a condition presents. This information is intended for educational purposes only and should not be used to make medical decisions. If you have concerns about your vision or family history, you should consult with a medical geneticist or an ophthalmologist who specializes in inherited retinal diseases.
How common is this variant?
The rs121912526 variant is extremely rare in the general population, with no significant frequency data available across major ancestral groups.
Frequently asked questions
What is congenital stationary night blindness?
Congenital stationary night blindness is a group of genetic disorders that affect the retina, making it difficult to see in low-light conditions. The term 'stationary' means that the condition is present from birth and does not typically get worse over time.
Is the rs121912526 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 clinical settings.
Can I get tested for this variant?
Genetic testing for specific rare variants is usually performed by clinical laboratories when a doctor suspects an inherited retinal condition. You should discuss the necessity of such testing with an ophthalmologist or a genetic counselor.
Does having this variant mean I will lose my vision?
The rs121912526 variant is associated with night blindness, which is a specific visual impairment. It is not the same as total blindness, and the progression of symptoms can vary between individuals.
Sources & further reading
Educational information only, last refreshed 10/10/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Pathogenic missense variant causing rhodopsin Pro23His substitution that leads to autosomal dominant retinitis pigmentosa and progressive night blindness.
Encodes the Pro23His (P23H) substitution in rhodopsin, the most common autosomal dominant retinitis pigmentosa allele in North America.
A non-synonymous variant altering rhodopsin protein structure that causes autosomal dominant retinitis pigmentosa with progressive rod photoreceptor loss.
Rhodopsin missense variant (p.Pro23His) responsible for classical autosomal dominant retinitis pigmentosa with rod photoreceptor degeneration.
Classic Pro23His (p.P23H) mutation in rhodopsin causing autosomal dominant retinitis pigmentosa.
A missense substitution (p.Arg135Trp) within rhodopsin's cytoplasmic loop that causes severe autosomal dominant retinitis pigmentosa through defective phototransduction signaling.