TCHH rs11803708: What Your Genotype Means
The rs11803708 variant is a common single nucleotide polymorphism located within the TCHH gene. Research suggests this variant is associated with differences in hair texture, specifically influencing straight versus curly hair morphology in individuals of European descent.
What each genotype means
Increased likelihood of curly hair
Carrying two C alleles at this marker is statistically associated with a higher likelihood of wavy or curly hair texture rather than straight hair in individuals of European ancestry. Hair morphology is polygenic, meaning multiple genes and structural follicle factors also shape final curliness. Because this is a benign physical trait, this genetic result carries no medical or health significance.
Found in approximately 40% to 45% of European populations; it is the predominant genotype across East Asian and African ancestries.
Intermediate hair curliness likelihood
Carrying one copy of the straight-hair associated T allele and one C allele is linked to intermediate odds of having wavy or straight hair. In European populations, the T allele acts in an additive manner to shift hair morphology toward a straighter appearance. This genetic variation represents natural physical variation and has no impact on personal health or well-being.
Present in roughly 45% of individuals of European descent, while being relatively uncommon in most East Asian populations.
Increased likelihood of straight hair
Having two copies of the derived T allele is strongly associated with straight hair morphology among European cohorts. While this locus accounts for a measurable portion of European hair shape variation, overall hair texture is also modulated by other genetic loci and environmental factors. This finding is purely cosmetic and does not affect your health.
Carried by approximately 10% to 15% of people of European ancestry, and rare to absent in East Asian and African populations.
Understanding the Variant
The rs11803708 variant is a single nucleotide polymorphism (SNP) situated within the TCHH gene, which encodes the protein trichohyalin. In genomics, a SNP represents a variation at a single position in the DNA sequence among individuals. This specific variant has been identified through genetic studies as a marker of interest regarding human physical traits. While many SNPs have no observable effect on a person's appearance or health, others are located in regions of the genome that influence how proteins are expressed or function. The rs11803708 variant is categorized as a trait-associated polymorphism, meaning it is statistically linked to a specific observable characteristic rather than a disease state. Because it is located in a gene involved in hair follicle structure, it has become a focal point for researchers studying the genetic basis of hair texture variation.
The Role of the TCHH Gene
The TCHH gene provides the instructions for creating the protein trichohyalin. This protein is primarily expressed in the hair follicles, which are the specialized structures in the skin responsible for hair growth. Trichohyalin acts as a molecular adaptor, helping to organize and cross-link keratin intermediate filaments. By forming these structural complexes, the protein provides mechanical strength and integrity to the inner root sheath of the hair follicle and the hair shaft itself. When the TCHH gene functions normally, it supports the structural remodeling required for healthy hair development. Conversely, significant disruptions or rare pathogenic mutations in this gene have been linked to conditions like uncombable hair syndrome, where a deficiency in functional protein leads to changes in the cross-section of the hair shaft, resulting in a distinct, frizzy texture.
Research and Evidence
Current research into rs11803708 indicates that it is associated with hair texture, particularly in European populations. Studies have observed that this polymorphism correlates with the prevalence of straight hair. However, it is important to note that the evidence strength for this association is considered limited. Hair texture is a complex, polygenic trait, meaning it is influenced by the interaction of many different genes rather than a single variant. While rs11803708 may contribute to the variation observed in hair morphology, it is only one piece of a much larger genetic puzzle. Other genes, such as those involved in keratin production and follicle development, also play significant roles. Because human traits are rarely determined by a single SNP, the predictive power of this variant for an individual's hair texture is not absolute and should be viewed as a statistical association rather than a definitive cause.
Population Frequency
The rs11803708 variant is relatively common in specific populations. Data indicates a minor allele frequency (MAF) of approximately 0.35 in European populations. This frequency suggests that the variant is widely distributed across these groups, reflecting its role as a common polymorphism rather than a rare mutation. Because genetic architecture varies significantly across different ancestral backgrounds, the associations observed in European cohorts may not necessarily translate to other populations. Genetic studies often highlight that traits like hair texture are influenced by different genes and variants depending on the ethnic background of the individuals studied. Therefore, the prevalence and the functional impact of this specific SNP are most relevant when discussed within the context of European ancestry.
Interpreting Your Information
Information regarding the rs11803708 variant is intended for educational purposes and should not be used for medical diagnosis or to make health-related decisions. Because this variant is associated with a physical trait rather than a clinical condition, it does not provide information about your health status or disease risk. If you are curious about your own genetic makeup, it is helpful to remember that traits like hair texture are the result of complex interactions between your genes and environmental factors. You cannot change your genotype, and knowing your status for this SNP does not alter your physical characteristics. If you have concerns about hair health or specific dermatological conditions, the most appropriate course of action is to consult with a qualified healthcare professional or a dermatologist who can provide personalized guidance based on your clinical history.
How common is this variant?
The rs11803708 variant is a common polymorphism with a minor allele frequency of approximately 0.35 in European populations.
Frequently asked questions
Does this variant mean I will have straight hair?
No, this variant is only one of many genetic factors that influence hair texture. While it is statistically associated with straight hair in Europeans, it cannot definitively predict your hair type.
Can I use this information to diagnose a hair condition?
No, this variant is associated with normal trait variation, not a medical condition. If you have concerns about your hair or scalp, please consult a dermatologist.
Is this variant found in all populations?
Genetic variants often show different frequencies across ancestral groups. This specific association is primarily documented in populations of European ancestry.
What is the TCHH gene responsible for?
The TCHH gene encodes the protein trichohyalin, which helps organize keratin filaments in hair follicles. This process is essential for maintaining the structural integrity of the hair shaft.
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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Key genetic variant within trichohyalin that shapes hair curliness, wave pattern, and texture in individuals of European ancestry.
Trichohyalin variant associated with hair curliness in individuals of European descent.
Missense coding variant in trichohyalin that plays a major determinant role in human straight versus curly hair morphology.
This variant in the trichohyalin gene influences hair texture, specifically associated with straight, wavy, or curly hair phenotypes.
Variant in the TCHH gene associated with variation in hair curl structure.
Trichohyalin gene variant associated with straight versus curly hair morphology and texture differences in populations of European descent.