Vitiligo is a skin condition closely related to skin colour. Indeed, by causing the depigmentation of the epidermis, it leads to the appearance of white patches on the skin surface, which contrast more or less strongly depending on skin tones. Thus, these patches are often more visible on darker skin. But does this difference in visibility mean that the frequency of vitiligo also varies according to skin colour? Let's explore this question together.
Dark skin or light skin: Does vitiligo occur at the same frequency?
Published on November 19, 2024, by Pauline, Chemical Engineer — 5 min of reading
Themes:
Does vitiligo have a different prevalence depending on skin colour?
Vitiligo is a skin disease resulting from the loss of melanocytes. To clarify, melanocytes are the cells that synthesize melanin, the pigment that gives skin its color. Depending on phototypes, the amount of melanin synthesized by melanocytes varies, which explains the diversity of skin tones. However, in the case of vitiligo, genetic factors, autoimmune responses, anti-inflammatory reactions, and oxidative stress-related factors cause the destruction of melanocytes, and thus the end of melanin synthesis. The skin then appears completely white in certain areas. Generally manifesting equally among the sexes, vitiligo has a global prevalence of about 0.5% to 2%.
However, prevalence rates vary geographically and are often higher in Africa and India. Furthermore, several studies seem to indicate that vitiligo affects more people with a Fitzpatrick skin type of III or IV . These are individuals with medium to dark skin, with warm and bronze undertones. Notably, two studies, conducted with 607 and 471 vitiligo patients respectively, focused on the prevalence of vitiligo according to skin type. The results of these studies are compiled in the table below.
| Study | Phototype I | Skin Type II | Phototype III | Phototype IV | Phototype V | Skin Type VI |
|---|---|---|---|---|---|---|
| MARTINS & al. (2013) | 4 (0.7%) | 85 (14%) | 248 (40.9%) | 208 (34.3%) | 58 (9.6%) | 4 (0.7%) |
| HARRIS & al. (2022) | 16 (3.4%) | 92 (19.5%) | 195 (41.4%) | 147 (31.2%) | 21 (4.5%) | 0 (0%) |
Prévalence du vitiligo selon les phototypes de Fitzpatrick.
It would therefore appear that vitiligo is particularly prevalent in individuals with a phototype of III or IV.
However, this does not mean that individuals with very dark or very light skin are spared from this disease. Furthermore, while the psychological impact of vitiligo should be considered regardless of an individual's skin colour, it is particularly resonant among populations with dark skin and/or in regions of the world where social and cultural stigmas are prevalent. This difference in perception between phototypes was indeed demonstrated in a recent study conducted with 123 patients. Among them, 96 had "light" skin (phototypes I to III) and 27 had "dark" skin (phototypes IV to VI). Individuals with dark skin were more likely to "suffer from the gaze of others" (68.2% versus 41.4%), to "fear repercussions on their physical appearance" (68.2% versus 53.3%) and to "consider vitiligo as a handicap" (50% versus 29.4%).
How can we explain the differences in the prevalence of vitiligo according to skin colours?
The etiology of vitiligo is the same across all phototypes and stems from the loss of melanocytes, as previously explained. However, this is partially influenced by genetic factors. Indeed, over 50 susceptibility genes have been associated with vitiligo, such as HLA, CTLA4, NLRP1, and TYR. It is therefore possible that the differences in prevalence observed between phototypes are due to a still low level of mixing between people of different skin colours, leading to a reproduction and a segregation of genes within the same communities.
Sources
MARTINS L. & al. A study of clinical profiles of vitiligo in different ages: an analysis of 669 outpatients. International Journal of Dermatology (2013).
EZZEDINE K. & al. Le fardeau du vitiligo : évaluation selon le phototype. Annales de Dermatologie et de Vénéréologie (2014).
EZZEDINE K. & al. Vitiligo: A Review. Dermatology (2020).
HARRIS J. & al. Vitiligo prevalence and quality of life among adults in Europe, Japan and the USA. Journal of the European Academy of Dermatology and Venereology (2022).
