rs191788703: Strabismus Risk and Genetics
The genetic variant rs191788703 is a single-nucleotide polymorphism located on human chromosome 12. Genome-wide association research has linked this variant to an increased statistical susceptibility to strabismus, a condition characterized by misalignment of the eyes. This association was identified primarily within individuals of Admixed American genetic ancestry, while the variant remains extremely rare in other global populations.
What each genotype means
Typical risk profile
You carry two copies of the common C allele at rs191788703. In genetic association studies, this baseline genotype is not associated with an increased genetic susceptibility to strabismus (eye misalignment).
Carried by approximately 94% to 95% of individuals of Admixed American ancestry and more than 99% of individuals of African and European ancestries.
Increased strabismus susceptibility
You carry one copy of the A allele at rs191788703. Research from genome-wide association studies has linked this variant to an increased statistical risk of strabismus, specifically identified in cohorts of Admixed American genetic ancestry. Carrying this variant does not mean you have or will develop strabismus, as eye alignment involves multiple genetic and environmental factors.
Carried by approximately 5% of individuals of Admixed American ancestry, but found in fewer than 0.1% of individuals of African or European ancestries.
Increased strabismus susceptibility
You carry two copies of the less common A allele at rs191788703. In published association studies, the A allele is statistically correlated with an elevated susceptibility to strabismus in Admixed American populations. This association reflects a population-level statistical correlation rather than a medical diagnosis or certainty of developing misaligned eyes.
Very rare, observed in less than 0.1% of individuals across all major global populations, including Admixed American ancestry.
Genomic Location and Biological Context
The single-nucleotide polymorphism rs191788703 represents a specific genomic locus situated on chromosome 12 (specifically at coordinate 12:130665032 under reference build GRCh38), involving a cytosine-to-adenine (C>A) substitution. In published multi-ancestry association analyses, this variant is mapped to an intronic or adjacent non-coding region of the RIMBP2 gene locus, though some catalog annotations designate it as an intergenic marker depending on the transcript reference model applied. Because it falls outside protein-coding exons, the variant does not alter amino acid sequences directly. Instead, non-coding single-nucleotide variants typically exert biological effects through subtle regulatory roles, such as altering transcription factor binding motifs, modifying regional chromatin architecture, or modulating transcript splicing. RIMBP2 encodes RIMS-binding protein 2, a presynaptic scaffold protein essential for organizing active zones and mediating fast neurotransmitter release across neuronal synapses, an interesting physiological context given the precise neural circuitry required for ocular motor control.
Research Findings and Evidence Strength
Evidence linking rs191788703 to ocular health originates from large-scale multi-ancestry analyses conducted through the National Institutes of Health All of Us Research Program. Researchers evaluated developmental strabismus across distinct ancestral cohorts, deliberately excluding adult-onset secondary forms caused by head trauma, thyroid eye disease, stroke, or orbital tumors. In the Admixed American (AMR) cohort, rs191788703 attained formal genome-wide statistical significance (p = 3.50 × 10⁻⁸) for its association with developmental strabismus. Despite this clear statistical signal, the evidence strength is currently considered moderate and exploratory. The finding has emerged from a single biobank-scale discovery dataset and has not yet undergone independent, cross-cohort replication. Furthermore, expression quantitative trait locus (eQTL) analyses did not show that rs191788703 directly drives measurable shifts in gene expression across tested tissues, indicating that the true causative functional variant within the local haplotype block remains to be elucidated.
Ancestry and Population Frequency
A defining characteristic of rs191788703 is its marked variation across diverse global ancestries. In the All of Us whole-genome sequencing dataset, the minor A allele demonstrated a frequency of approximately 2.77% (0.0277) within the Admixed American population cohort. By stark contrast, the allele is virtually absent or exceptionally rare among other ancestral populations, exhibiting an allele frequency of roughly 0.041% (0.00041) in individuals of African ancestry and 0.0017% (0.0000169) in individuals of European ancestry. Because the minor allele frequency falls well below 1% in most non-American ancestral lineages, cross-ancestry meta-analyses were statistically unfeasible. This dramatic divergence illustrates why multi-ancestry genomic cohorts are critical: common European-centric association screens fail to detect loci whose risk-conferring alleles are informative exclusively within non-European or admixed backgrounds.
Practical Implications for Personal Genetics
Discovering an alternate allele at rs191788703 on a direct-to-consumer genetic report or whole-genome sequence does not indicate that an individual has or will inevitably develop strabismus. Strabismus is an etiologically complex visual disorder influenced by numerous polygenic variants alongside environmental factors, early childhood visual input, and refractive errors such as hyperopia. Single-nucleotide variants identified through genome-wide scans confer modest relative risks rather than deterministic clinical outcomes. Genetic data for rs191788703 cannot diagnose amblyopia, determine muscular misalignment severity, or guide surgical planning. Visual screening and comprehensive clinical examinations performed by pediatric ophthalmologists or optometrists remain the standard method for assessing ocular alignment, binocular vision, and ocular motor coordination.
How common is this variant?
The minor A allele is observed at low frequency in Admixed American populations (approximately 2.8%), while remaining extremely rare across African (under 0.05%) and European (under 0.002%) ancestral groups.
Frequently asked questions
What is rs191788703?
The marker rs191788703 is a single-nucleotide variant located on chromosome 12 near the RIMBP2 gene. It was identified in large-scale genetic research as a potential contributor to strabismus susceptibility in specific ancestral groups.
Does having the rs191788703 variant mean I will develop crossed eyes?
No. Strabismus is a complex polygenic condition influenced by many genes and environmental factors. Carrying a risk allele slightly alters statistical susceptibility, but it is not deterministic and cannot cause misalignment on its own.
Why is this variant only studied in Admixed American populations?
The minor allele occurs at an informative frequency of about 2.8% in Admixed American groups, but is virtually absent (less than 0.05%) in European and African lineages. Statistical association studies require a variant to appear frequently enough in a population to evaluate its link to health traits.
Can doctors use this genetic variant to guide eye surgery?
No. Management of strabismus relies entirely on clinical ocular exams, alignment measurements, and visual function assessments. The variant has no current utility in clinical decision-making, medical diagnosis, or surgical planning.
Sources & further reading
Educational information only, last refreshed 9/13/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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