EDAR rs615563: Understanding the Variant and Hair Morphology
The rs615563 variant is a well-studied genetic marker located within the EDAR gene. It is strongly associated with variations in hair fiber thickness and crown morphology, particularly in populations of East Asian ancestry.
What each genotype means
Typical hair thickness
This genotype is the ancestral form of the variant. It is associated with thinner hair fiber morphology compared to the derived G allele found in many East Asian populations.
This genotype is the most common form in European and African populations, but is rare in East Asian lineages.
Intermediate hair thickness
Carrying one copy of the derived G allele may contribute to intermediate hair fiber thickness. This variant is part of a gene known to influence hair morphology, sweat gland density, and dental traits.
This heterozygous genotype is observed in populations where both ancestral and derived alleles are present, particularly in admixed groups.
Increased hair thickness
This genotype is strongly associated with increased hair fiber thickness and is a well-documented signal of natural selection in East Asian and Native American populations. It is also linked to other ectodermal traits, such as variations in sweat gland density and tooth morphology.
This genotype is highly prevalent in East Asian and Native American populations, reaching frequencies of 70-90% in some groups.
What is the rs615563 Variant?
The rs615563 variant is a single nucleotide polymorphism (SNP) located within the EDAR gene, which sits on chromosome 2. In the context of human genetics, this variant is frequently discussed alongside the specific amino acid change it influences, often referred to in scientific literature as V370A. This means that at a specific position in the protein, the ancestral valine (V) is replaced by alanine (A). This change is not a random mutation but is considered a derived variant that has undergone significant positive selection in certain human populations. Because it is located in a region of the gene that affects protein function, it alters the signaling output of the receptor. Researchers study this SNP to understand how specific genetic changes can lead to observable physical differences, such as the texture and thickness of hair, which vary significantly across different global ancestries.
The Role of the EDAR Gene
The EDAR gene provides instructions for making a protein called the ectodysplasin A receptor. This receptor is a critical component of a signaling pathway that is active before birth and throughout life, playing a fundamental role in the development of ectodermal structures. These structures include hair follicles, sweat glands, and teeth. By acting as a receptor, the EDAR protein receives signals that help coordinate the growth and differentiation of these tissues. When this signaling pathway functions normally, it ensures the proper formation of these appendages. Because of its essential role in development, mutations in the EDAR gene can sometimes lead to medical conditions, such as hypohidrotic ectodermal dysplasia, which affects the development of sweat glands, teeth, and hair. However, the common variant rs615563 is a functional polymorphism that contributes to normal human variation in hair traits rather than causing a clinical disorder.
Research and Evidence
Scientific research has established a strong statistical association between the rs615563 variant and hair morphology. Studies have demonstrated that the derived allele, which is common in East Asian populations, results in a more potent signaling output compared to the ancestral version of the receptor. This enhanced signaling is linked to thicker hair fibers and specific crown morphology. The evidence for this association is considered robust within the field of human evolutionary genetics, as the variant shows one of the strongest signals of natural selection in the human genome. While the link to hair thickness is well-supported by multiple studies, it is important to note that hair traits are polygenic, meaning they are influenced by many different genes working in concert. Therefore, while rs615563 is a major contributor, it is only one piece of a much larger genetic puzzle that determines an individual's hair characteristics.
Population Frequency
The distribution of the rs615563 variant is highly distinct across different ancestral groups. It is found at a very high frequency in East Asian and Native American populations, often ranging between 70% and 90%. In contrast, this specific variant is extremely uncommon or nearly absent in European and African ancestries. This striking frequency difference is a classic example of how natural selection can drive a specific genetic variant to high prevalence in one geographic region while it remains rare elsewhere. Researchers believe this pattern suggests that the variant may have provided an evolutionary advantage in the environments where it became common, though the exact nature of that advantage remains a subject of ongoing scientific investigation. Understanding this population-specific distribution is crucial for researchers when conducting genetic studies to ensure that findings are interpreted within the correct ancestral context.
What This Information Means for You
Learning about your genotype for rs615563 provides insight into the genetic factors that contribute to your physical traits, such as hair thickness. It is important to remember that this information is for educational purposes and describes statistical associations observed in large populations. It does not provide a medical diagnosis or predict your exact physical appearance, as many other genetic and environmental factors also play a role. You cannot use this information to make medical decisions or to diagnose any health conditions. If you have concerns about your hair, skin, or dental health, it is always best to consult with a qualified healthcare professional or a dermatologist. Genetic information is a tool for understanding human diversity and evolutionary history, but it should not be used as a substitute for professional medical advice or clinical evaluation.
How common is this variant?
The rs615563 variant is highly prevalent in East Asian lineages, with frequencies typically between 0.70 and 0.90, while it remains uncommon in European and African ancestries.
Frequently asked questions
Is the rs615563 variant a disease-causing mutation?
No, rs615563 is a common genetic variant associated with normal human variation in hair traits. It is not considered a disease-causing mutation, although the EDAR gene itself is involved in conditions like ectodermal dysplasia when rare, pathogenic mutations occur.
Can I change my hair thickness based on my EDAR genotype?
No, your genotype is determined at conception and cannot be changed. While your genetics influence your hair thickness, environmental factors and hair care practices also play a significant role in the appearance and health of your hair.
Why is this variant so common in East Asia?
Research suggests that the variant underwent strong positive selection in East Asian populations. This means it likely provided an evolutionary advantage in the past, causing it to increase in frequency over many generations.
Does this variant affect my health?
The rs615563 variant is primarily associated with physical traits like hair thickness and is not typically linked to health issues. If you have specific health concerns, you should consult with a medical professional rather than relying on genetic trait information.
Sources & further reading
Educational information only, last refreshed 9/27/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Functional variant tightly linked to hair shaft thickness, sweat gland density, and distinct East Asian dental morphology traits.
Functional variant (V370A) in the EDAR gene influencing hair thickness and sweat gland density.
Intronic regulatory variant tightly linked to hair follicle density, incisor shoveling morphology, and sweat gland branching in continental Asian populations.
The 370A (Val370Ala) variant is a classic example of positive selection in East Asian and Native American populations, affecting hair thickness and sweat gland density.
Common regulatory variant in the EDAR region associated with variation in human hair thickness, beard density, and facial shape.
Functional variant in EDAR associated with hair fiber diameter and dental morphology.