CRX rs104894489: Understanding This Rare Genetic Variant
The rs104894489 variant is a rare genetic change located within the CRX gene, which plays a critical role in the development and maintenance of retinal photoreceptor cells. It is primarily studied in the context of inherited retinal diseases that affect vision.
What each genotype means
Typical CRX gene profile
This genotype represents the most common sequence found in the general population for this specific location in the CRX gene. It is considered the reference state, and there is no evidence suggesting this specific configuration contributes to retinal disease.
This is the predominant genotype observed in the vast majority of the human population.
Rare CRX variant carrier
This genotype indicates the presence of one copy of the rare variant. Because this variant is located in the CRX gene, which is essential for photoreceptor development, any clinical significance remains uncertain and requires professional evaluation if symptoms of retinal dysfunction are present.
This genotype is extremely rare, with an allele frequency reported at less than 0.00001 in large-scale population databases.
Rare CRX variant homozygous
This genotype indicates that both copies of the CRX gene carry this rare variant. Given the critical role of CRX in maintaining retinal photoreceptor cells, this configuration warrants careful clinical correlation with an ophthalmologist or genetic counselor to determine if it relates to any observed retinal health concerns.
This genotype is exceptionally rare and is not typically observed in standard population screening cohorts.
What is rs104894489 and Where is it Located?
The variant rs104894489 is a specific change in the DNA sequence of the CRX gene. In genomics, a single nucleotide polymorphism (SNP) like this represents a variation at a single position in the genome. This particular variant is classified as a missense mutation, meaning the change in the DNA code results in a different amino acid being incorporated into the resulting protein. The CRX gene is located on chromosome 19. Because this variant is extremely rare, it is not typically found in the general population, and its presence is usually identified through specialized clinical genetic testing rather than routine screening. Understanding its location within the homeodomain of the CRX protein is essential, as this region is vital for the protein's ability to bind to DNA and regulate the expression of other genes necessary for healthy vision.
The Role of the CRX Gene
The CRX gene provides the instructions for creating the cone-rod homeobox protein. This protein functions as a transcription factor, which acts like a master switch in the cell. Its primary job is to turn other genes on or off, specifically those required for the differentiation and survival of photoreceptor cells in the retina. Photoreceptors are the specialized cells in the eye that detect light and convert it into electrical signals that the brain interprets as vision. There are two main types: rods, which function in low light, and cones, which are responsible for color vision and fine detail. When the CRX protein is functioning correctly, it ensures these cells develop properly and maintain their identity throughout a person's life. Disruptions to this gene can interfere with these processes, potentially leading to the degeneration of retinal cells.
Research Associations and Evidence Strength
Scientific research has linked various mutations in the CRX gene to a spectrum of inherited retinal diseases, including Leber congenital amaurosis, cone-rod dystrophy, and retinitis pigmentosa. These conditions are characterized by the progressive loss of photoreceptor cells, leading to vision impairment. The evidence for the pathogenicity of specific CRX variants is often derived from clinical studies of families affected by these conditions. However, the evidence strength for any single rare variant like rs104894489 can be limited, as researchers must distinguish between disease-causing mutations and benign sequence variations that do not impact health. Current studies utilize multi-omics approaches and in vitro models to understand how specific missense mutations alter the DNA-binding specificity of the CRX protein. Because these conditions are rare, clinical data is often gathered from small cohorts, meaning our understanding of the full phenotypic spectrum continues to evolve as more research is published.
Population Frequency
The rs104894489 variant is considered ultra-rare, with a reported allele frequency of less than 0.00001 in the gnomAD database. This extremely low frequency indicates that the variant is not a common polymorphism found in the general population.
Navigating Genetic Information
If you have received information about a rare variant like rs104894489 through genetic testing, it is important to understand that this information is complex and requires professional interpretation. Genetic variants do not always lead to disease, and the presence of a variant must be correlated with clinical symptoms and family history by a qualified healthcare provider. You cannot use this information to diagnose yourself or predict specific health outcomes without clinical context. If you are concerned about your vision or a family history of retinal disease, consult with a genetic counselor or an ophthalmologist who specializes in inherited retinal conditions. They can help explain the significance of your results, discuss the limitations of current scientific knowledge, and provide guidance on appropriate clinical follow-up or management strategies tailored to your specific situation.
How common is this variant?
The rs104894489 variant is ultra-rare, with a gnomAD allele frequency of less than 0.00001.
Frequently asked questions
What is the CRX gene?
The CRX gene encodes a transcription factor called the cone-rod homeobox protein. It is essential for the development and survival of photoreceptor cells in the retina.
Are all CRX variants harmful?
No, not all variants in the CRX gene are harmful. Many sequence variations are benign and do not affect the function of the protein or cause disease.
What should I do if I have a rare CRX variant?
If you have identified a rare variant, you should discuss the results with a genetic counselor or an eye specialist. They can provide context based on your personal and family medical history.
Is there a cure for CRX-related retinal diseases?
Currently, there is no universal cure for inherited retinal diseases caused by CRX mutations. Research is ongoing into gene therapies and other treatments to manage these conditions.
Sources & further reading
Educational information only, last refreshed 9/22/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Pathogenic homeodomain mutation associated with autosomal dominant cone-rod dystrophy and Leber congenital amaurosis.
A dominant missense variant in the CRX homeobox transcription factor causing Leber congenital amaurosis and cone-rod dystrophy.
This variant in the cone-rod homeobox transcription factor gene causes autosomal dominant cone-rod dystrophy and Leber congenital amaurosis.
Pathogenic missense variant in the CRX homeodomain associated with autosomal dominant cone-rod dystrophy and severe visual impairment.
Encodes the Glu80Ala missense change in the cone-rod homeobox factor, causing autosomal dominant cone-rod dystrophy and severe visual acuity decline.
This pathogenic variant in the CRX gene is linked to Retinitis pigmentosa, affecting retinal photoreceptor development.