Skin and Hair Genetics: What a DNA Test Reveals

A young woman looking into a handheld mirror with a focus on natural skin texture and neck area — main cover image.

Appearance is one of the most visible manifestations of human biological variability. Differences in skin properties and pigmentation, and in the structure and life cycle of hair, are shaped by many factors, among which genetic ones make a contribution that depends on the specific trait.

For most of these characteristics there is no single determining gene. Their genetic architecture is polygenic: numerous variants may each make a small contribution to the biological systems involved in the formation and functioning of skin and hair follicles. This combination of differences explains why people of a similar age, with a similar lifestyle and in virtually identical environmental conditions, can have different phenotypes.

Two Levels of Information About Appearance

Dermatological examination, photographic documentation, and other phenotype assessment methods record the current state of the skin and hair: rashes, degree of dryness, signs of irritation, patterns of hair changes, and already established signs of aging.

Genetic analysis, by contrast, describes inherited variants associated with how certain biological systems function throughout life. For skin, this may concern processes related to the immune response, barrier function, pigmentation, and age-related changes. For hair — pigmentation traits, graying, follicle structure, and some forms of its sensitivity to hormonal signals.

At the same time, a genetic result does not determine what the phenotype of the skin and hair will be in the future. It characterizes the hereditary component of phenotypic variability, whereas the phenotype is formed through the interaction of genetic factors with the environment and other factors.

Skin Reactivity and Genetics

The condition of the skin depends on the interaction between the external environment and the body's internal processes: it is affected by external irritants (mechanical friction or pressure, chemicals, ultraviolet radiation, microorganisms on its surface, temperature fluctuations) and by internal processes (hormonal background and immune activity), which act as independent factors and shape the pattern of response to external irritants.

People can respond differently to similar stimuli, and this is linked to variants in genes involved in the regulation of the inflammatory response — in particular IL13 (interleukin 13) and IL23R (interleukin 23 receptor). This link is supported, among others, by a large genome-wide association study (GWAS), which identified 81 loci associated with susceptibility to atopic dermatitis (Budu-Aggrey et al., Nature Communications, 2023).

The genetic architecture of psoriasis is also polygenic. In a meta-analysis of 18 GWAS, researchers analyzed 36,466 cases and 458,078 controls and identified 109 loci associated with susceptibility to psoriasis (Dand et al., Nature Communications, 2025).

These results do not mean that a specific gene causes a disease or acts in isolation on, for example, barrier function. Rather, genetic differences may be associated with susceptibility to a disease or with impaired barrier function.

For the role of external triggers and their weight in individual skin reactions, see the article Acne, Psoriasis, Atopic Dermatitis: When Skin Reacts to More Than a Cream.

Schematic 3D cross-section of epidermal and dermal layers showing interwoven collagen fibers and a glowing active zone.

Skin Aging Genetics

Skin aging is the result of two overlapping processes: endogenous (chronological aging, related to age) and exogenous (driven by external factors — above all the cumulative effect of ultraviolet radiation, i.e. photoaging).

With age, the structure of the dermis changes — in particular type I collagen, encoded by the COL1A1 gene (collagen type I alpha 1 chain), and the elastic fibers, whose formation is governed by the ELN gene (elastin). The breakdown of damaged collagen is regulated by an enzyme encoded by the MMP1 gene (matrix metalloproteinase 1). With age, the balance between the synthesis and breakdown of these structures shifts (Wahhab et al., Journal of the American Academy of Dermatology, 2025). A systematic review and meta-analysis of 48 studies identified 30 loci associated with skin aging phenotypes. The authors also note that the studies in the review differed in their samples and in the ways the phenotype was assessed (Wong et al., Journal of Physiological Anthropology, 2025).

Thus, genetic variants may be linked to processes that affect the structure and aging of the skin, but they do not determine the exact date when wrinkles appear or how pronounced age-related changes will become over time. The degree to which a genetic predisposition shows itself depends on environmental factors: how much ultraviolet radiation the skin has received and receives, how a person cares for it, whether they have harmful habits such as smoking, how they eat, what comorbidities they have, and which medications they take.

For more on the mechanisms of skin aging, collagen, and photoaging, see the article Skin Aging, Collagen, and Photoaging: What Is Written in Your DNA.

Genetics of Skin, Hair, and Eye Pigmentation

The color of skin, hair, and eyes is determined by the amount, type, and ratio of melanin — a pigment produced by melanocytes. The two main types of melanin — the darker eumelanin and the lighter, yellow-red pheomelanin — are present in every person in different proportions depending on their genetic profile. It is this proportion that shapes the shade of skin, hair, and eyes (Manga & Loftus, Annals of Human Genetics, 2025).

A key role in melanin synthesis is played by the MC1R gene (melanocortin 1 receptor): it influences the balance in the production of different types of melanin in melanocytes. A reduced-function variant of this gene shifts the balance toward pheomelanin, which is associated with red hair, fair skin, and a reduced ability of the skin to tan in response to ultraviolet radiation.

The genes TYR (tyrosinase), SLC24A5 (solute carrier family 24 member 5), and SLC45A2 (solute carrier family 45 member 2) are also responsible for melanin synthesis and distribution — variants of these genes are among the main contributors to differences in skin tone between populations. Eye color is mainly linked to the HERC2 gene (HECT and RLD domain containing E3 ubiquitin protein ligase 2), which regulates the activity of the neighboring OCA2 gene (OCA2 melanosomal transmembrane protein) and, together with it, determines the amount of melanin in the iris.

Genetics of Hair Color, Hair Loss, and Graying

Hair color, hair loss, and graying are the outcome of different biological mechanisms, although some of them partly overlap at the level of individual genes. Studies do identify such links, but a single genetic finding does not explain every hair problem.

A GWAS of hair characteristics that included more than 6,000 participants identified genetic associations with hair color, graying, and baldness. For graying, one of the most notable signals was a variant in the IRF4 gene (interferon regulatory factor 4), linked to the regulation of pigmentation. For baldness, signals in the region of the AR (androgen receptor) and EDA2R (ectodysplasin A2 receptor) genes were, among others, confirmed (Adhikari et al., Nature Communications, 2016).

Androgenetic alopecia also has a polygenic nature. Current reviews describe the involvement not only of the androgen signaling system but also of hair follicle development, cell viability, and extracellular matrix remodeling (Gupta et al., Biology, 2026).

Androgenetic alopecia is only one of the possible causes of hair thinning. Other causes include vitamin or mineral deficiencies, illnesses, medication side effects, stressful events, or hormonal changes. Therefore, a genetic result should be considered together with the medical history, symptoms, and clinical assessment.

For early hair loss and the mechanisms of androgenetic alopecia, see the article Why Hair Falls Out at a Young Age Even When Hormones Are Normal: The Role of Genetics.

High-resolution 3D macro view of a single hair shaft showing overlapping cuticle scales and an illuminated core cortex.

A Genetic Result Among Other Sources of Information

The practical value of genetic testing for skin and hair depends on the question to be answered: assessing the hereditary component of a particular trait, such as skin reactivity or the pace of its aging, or finding the cause of a symptom that appeared recently. Genetic analysis can be informative in the first case, but it will not identify the cause of a new symptom.

In an acute clinical situation, genetic context can help assess the hereditary component of certain traits, such as heightened skin reactivity or a predisposition to hair loss, which may be related to the development of a specific symptom. At the same time, genetic test results do not replace instrumental or laboratory diagnostics but complement clinical assessment, helping to determine which features of skin and hair should be taken into account during further follow-up and whether the preventive approach needs to be revised to support long-term health.

Skin reactivity, pace of aging, hair color, and hair loss are traits whose genetic component can be explored with the «Skin, Hair and Appearance» DNA test or within the Ultima genetic panel, which covers more than 1,000 indicators and provides a complete genetic profile.

Genetic test results are not a diagnosis and are not a substitute for a doctor's consultation. The Apixmed Prism report provides genetic context that complements examination results and helps in making decisions together with a doctor.

Sources

1. Budu-Aggrey, A., Kilanowski, A., Sobczyk, M. K., et al. (2023). European and multi-ancestry genome-wide association meta-analysis of atopic dermatitis highlights importance of systemic immune regulation. Nature Communications, 14(1), 6172. https://doi.org/10.1038/s41467-023-41180-2

2. Dand, N., Stuart, P. E., Bowes, J., et al. (2025). GWAS meta-analysis of psoriasis identifies new susceptibility alleles impacting disease mechanisms and therapeutic targets. Nature Communications, 16(1), 2051. https://doi.org/10.1038/s41467-025-56719-8

3. Wahhab, R., Sanders, M., Kokikian, N., Ni, C., & Vandiver, A. R. (2025). Clinical consequences of age-related skin barrier dysfunction—Part I: Structural, molecular, and physiologic changes with cutaneous aging. Journal of the American Academy of Dermatology, 93(4), 905–914. https://doi.org/10.1016/j.jaad.2024.08.044

4. Wong, C., Ng, J. Y., Sio, Y. Y., & Chew, F. T. (2025). Genetic determinants of skin ageing: a systematic review and meta-analysis of genome-wide association studies and candidate genes. Journal of Physiological Anthropology, 44(1), 4. https://doi.org/10.1186/s40101-025-00384-9

5. Adhikari, K., Fontanil, T., Cal, S., et al. (2016). A genome-wide association scan in admixed Latin Americans identifies loci influencing facial and scalp hair features. Nature Communications, 7, 10815. https://doi.org/10.1038/ncomms10815

6. Gupta, A. K., Dennis, D. J., Economopoulos, V., & Piguet, V. (2026). The Genetic Landscape of Androgenetic Alopecia: Current Knowledge and Future Perspectives. Biology, 15(2), 192. https://doi.org/10.3390/biology15020192

7. Manga, P., & Loftus, S. (2025). Genetics of Skin, Hair, and Eye Color in Human Pigmentation Disorders. Annals of Human Genetics, 89(5), 305–320. https://doi.org/10.1111/ahg.70003