PIWIL4 rs118136100: Color Vision Variation and Genetics
The single nucleotide polymorphism rs118136100 is an autosomal genetic variant located within the PIWIL4 gene on human chromosome 11. Genome-wide association research has linked this variant to mild variations in red-green color discrimination, specifically deuteranomalous and protanomalous color vision defects. Discovered primarily in cohorts from historical Silk Road trading routes, it points toward complex non-opsin mechanisms in visual perception.
What each genotype means
Typical color vision predisposition
You carry two copies of the common C reference allele for rs118136100. In population studies evaluating red-green color discernment, this genotype is not linked to an elevated risk of deuteranomalous or protanomalous color vision defects. Research currently shows baseline visual function for this locus.
Carried by the vast majority of individuals globally, representing over 90% of genotypes across European, African, and East Asian populations.
Increased color vision defect likelihood
You carry one copy of the T effect allele at rs118136100 within the PIWIL4 gene region. Published genome-wide association findings, particularly in Central Asian and Silk Road populations, associate this allele with a higher susceptibility to red-green color vision defects such as deuteranomaly or protanomaly. Carrying this genotype indicates an elevated statistical probability rather than a definitive diagnosis of color vision deficiency.
Found in approximately 5% to 15% of individuals in Central Asian cohorts, but remains rare to low frequency in other global populations.
Elevated color vision defect likelihood
You carry two copies of the T effect allele at rs118136100. Research in Silk Road and related cohorts links the T variant to deuteranomalous or protanomalous red-green color vision defects. This genetic profile reflects a statistical correlation identified in population cohorts rather than a definitive medical condition, and formal clinical color vision assessment is necessary to determine functional vision phenotype.
Infrequent globally, observed in fewer than 1% to 2% of individuals in Central Asian groups and exceptionally rare elsewhere.
What is rs118136100 and Where Is It Located?
The variant rs118136100 is a single nucleotide polymorphism (SNP) situated on chromosome 11 within the PIWIL4 gene. In standard genomic reference builds, it represents a single base-pair substitution among individuals. Unlike the classical forms of red-green color blindness that map directly to the opsin gene cluster on the X chromosome, rs118136100 is inherited on an autosome. This distinction is notable because autosomal variants affect both biological males and biological females equally in terms of inheritance patterns. The variant was captured during high-density array genotyping and imputation studies designed to uncover complex genetic architectures contributing to human sensory variation. Because it sits within non-coding sequence of the PIWIL4 genomic region, it is hypothesized to influence regulatory mechanisms, such as transcript stability or expression level modulations, rather than producing a truncated or fundamentally broken protein structure.
Understanding the PIWIL4 Gene and Retinal Biology
The PIWIL4 gene encodes Piwi-like protein 4, an essential component of the Argonaute/PIWI protein family involved in RNA-mediated gene silencing, chromatin remodeling, and epigenetic regulation. While PIWIL4 is heavily recognized for controlling transposable elements and maintaining genomic stability in germline cells, molecular profiling databases demonstrate its expression in various somatic tissues, including the human retina and retinal pigment epithelium (RPE). The RPE forms a critical support monolayer immediately adjacent to the photoreceptor cells, providing nutrient transport, absorbing scattered light, and recycling visual pigments necessary for normal cone function. Functional hypotheses suggest that altered PIWIL4 activity could subtly modify gene expression programs or stress responses within the retinal microenvironment, thereby influencing how photoreceptors maintain long-term signaling efficiency without causing overt retinal degeneration.
The Scientific Evidence and the Silk Road Cohorts
Classical red-green color vision deficiency (CVD) has historically been attributed nearly exclusively to structural rearrangements or missense variants in the OPN1LW and OPN1MW genes on the X chromosome. However, an exploratory genome-wide association study (GWAS) investigating isolated human populations along historical Silk Road trade routes identified rs118136100 as a top-associated variant for deutan-protan (DP) phenotypes. The study observed a statistically significant signal linking the minor allele with shifts in deutan (green) and protan (red) cone spectral sensitivity. These findings provided empirical evidence that common and multifactorial color discrimination differences can involve regulatory modifier genes beyond the classic opsin arrays. Nonetheless, the evidence strength remains moderate; while the statistical threshold was robust in the discovery cohort, the findings reflect population-specific genetic architectures and require replication across larger global datasets.
Population Frequency and Ancestral Distribution
The distribution of rs118136100 shows distinct geographical variation. It was characterized as a candidate modifier of vision in genetic isolates from Central Asian and Silk Road populations, where centuries of trade and isolation fostered unique patterns of linkage disequilibrium and genetic admixture. In broader worldwide reference datasets, such as the Genome Aggregation Database (gnomAD), the variant appears with variable minor allele frequencies across major continental groupings. Because complex traits like sensory thresholds often depend on polygenic backgrounds and specific environmental exposures, the prevalence of this variant in Central Asian groups highlights the value of studying underrepresented communities to uncover novel functional loci that remain invisible in homogeneous cohorts.
What Consumers Can and Cannot Conclude
It is critical to distinguish between associative genetic research and clinical diagnostic screening. Carrying the minor allele at rs118136100 does not mean an individual is clinically color blind, nor does having the typical genotype guarantee flawless hue discrimination. Clinical color vision deficiency is formally diagnosed through validated psychophysical examinations—such as Ishihara pseudoisochromatic plates, the Farnsworth-Munsell 100 Hue Test, or anomaloscopy—performed by an optometrist or ophthalmologist. The PIWIL4 rs118136100 variant acts as a statistical modifier in research cohorts rather than a deterministic clinical marker. Consumers reviewing personal genomic data should view this variant as an educational insight into retinal physiology and multifactorial sensory genetics rather than actionable medical guidance.
How common is this variant?
The rs118136100 variant has been highlighted as a top-associated marker in Central Asian and Silk Road cohorts, with varying minor allele frequencies observed across broader global population registries.
Frequently asked questions
Does having the rs118136100 variant mean I am color blind?
No. The rs118136100 variant is merely associated with subtle statistical variations in red-green discrimination in population studies. It is not an X-linked opsin mutation that causes classic color blindness, and a formal diagnosis requires in-person testing by an eye care specialist.
How is rs118136100 different from classic red-green color blindness genes?
Classic red-green color blindness is caused by structural variations in the OPN1LW and OPN1MW opsin genes located on the X chromosome. In contrast, rs118136100 is located on chromosome 11 in the autosomal PIWIL4 gene, where it is thought to act as a regulatory modifier in the retina.
Can women be affected by the rs118136100 variant?
Yes. Because rs118136100 is located on an autosome (chromosome 11) rather than a sex chromosome, it is inherited equally by biological males and females, unlike classic X-linked recessive red-green color blindness.
Why was this variant specifically studied in Silk Road populations?
Silk Road populations represent historically admixed and genetically unique cohorts that offer high statistical power to detect previously undiscovered genetic variants linked to multifactorial traits, which are often missed in conventional Western-centric studies.
Sources & further reading
Educational information only, last refreshed 9/12/2026. Not medical advice — these associations describe population statistics, not individual predictions.
Curious what your genotype is for rs118136100?
Upload a raw DNA file from 23andMe, AncestryDNA, MyHeritage, or FamilyTreeDNA and see this variant — plus thousands more — interpreted in your full report.
Get my report — $29