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Ethnicity versus Climate: The Impacts of Genetics and Environment on Rosacea Epidemiology and Pathogenesis


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Rosacea is a chronic inflammatory cutaneous condition, characterized by facial redness in the first stages, followed by papules, pustules and deformities later on the course. The pathogenesis of the disease involves several factors, such as immunologic, infectious and environmental triggers. Genetic predisposing factors are also postulated due to the remarkably positive family history often found. Through a detailed literature review, we aim to qualify and quantify the impact of climatic versus genetic factors on rosacea epidemiology worldwide. Possible associations are here considered, including the higher prevalence of rosacea in fair-skinned individuals of Northern European descent, the influence of the latitude, cold weather, and the diagnostic inaccuracy in people with skin of color. Further, we discuss the roles of cold-induced vasodilation, the skin colonization by Demodex mites, and the findings from the most recent genetic studies in this field.
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Archives of Clinical & Experimental Dermatology
Review | Vol 2 Iss 1
Citation: Silva ACD, Ben Fadhel S. Ethnicity versus Climate: The Impacts of Genetics and Environment on Rosacea Epidemiology and
Pathogenesis. Arc Clin Exp Dermatol. 2020;2(1):109.
©2020 Yumed Text.
Ethnicity versus Climate: The Impacts of Genetics and Environment on
Rosacea Epidemiology and Pathogenesis
Ana Cristina Diniz Silva1* and Saima Ben Fadhel2
1Department of Postgraduate Studies, Dermatology and Cosmetic Medicine, University of South Wales, UK
2Medical Doctor, MSc, UK
*Corresponding author: Silva ACD, Department of Postgraduate studies, Dermatology and Cosmetic Medicine, University
of South Wales, UK; E-mail:
Received: June 01, 2020; Accepted: June 09, 2020; Published: June 16, 2020
1. Introduction
Rosacea is a common chronic inflammatory skin disease affecting 5% to 10% of the world population [1]. This condition
alters primarily the vasculature and the pilosebaceous units of the face resulting in variable levels of facial redness, from
intermittent flushing, persistent erythema and telangiectasia, to papules, pustules, and ultimately to phymata [2]. Based on its
morphological aspects, rosacea can be classified into four major subtypes, as shown in TABLE 1. However, in daily practice,
this classification does not reflect the clinical reality, since the different morphological characteristics of those subtypes
commonly coexist [1]. Rosacea more often occurs in fair-skinned individuals aged 45 to 60 years old, particularly in
populations with a predominant Celtic or northern European heritage. Much less commonly, this condition may also affect
people with darker skin phototypes [3].
Rosacea is a chronic inflammatory cutaneous condition, characterized by facial redness in the first stages, followed by
papules, pustules and deformities later on the course. The pathogenesis of the disease involves several factors, such as
immunologic, infectious and environmental triggers. Genetic predisposing factors are also postulated due to the remarkably
positive family history often found. Through a detailed literature review, we aim to qualify and quantify the impact of
climatic versus genetic factors on rosacea epidemiology worldwide. Possible associations are here considered, including the
higher prevalence of rosacea in fair-skinned individuals of Northern European descent, the influence of the latitude, cold
weather, and the diagnostic inaccuracy in people with skin of color. Further, we discuss the roles of cold-induced
vasodilation, the skin colonization by Demodex mites, and the findings from the most recent genetic studies in this field.
Keywords: Rosacea; Dermatology; Skin rash; Genetics; Epidemiology | June-2020
TABLE 1. Clinical Classification of Rosacea [1].
The diversity of rosacea’s clinical spectrum has made its etiology and pathophysiology elusive. Studies suggest that the
pathogenesis of rosacea involves inappropriate innate and adaptive immune responses to a wide spectrum of biological,
environmental and endogenous stimuli leading to an aberrant neurovascular signalling. Skin colonisation with certain
microorganisms, such as Demodex mites, seems to play a role as one of the various mediators of these events. Well
recognised environmental triggers include ultra-violet radiation, alcohol, cold, heat and physical activities. Certain
psychological factors such as stress can also cause the disease to flare up. Additionally, a positive family of rosacea is
commonly identifiable [3].
Through a detailed literature review, we aim to qualify and quantify the impact of climatic versus genetic factors on rosacea
epidemiology worldwide. Possible associations are here considered, including the higher prevalence of rosacea in fair-
skinned individuals and the diagnostic inaccuracy in people with skin of colour. Further, we discuss the role of cold-induced
vasodilation, the skin colonisation by Demodex mites, and the findings from the most recent genetic studies in this field.
2. Epidemiology
2.1. Rosacea in fair-skinned populations
The medical literature is consensual when stating that rosacea has a much higher prevalence among adults of Northern
European descent. Sun-sensitive skin, particularly phototypes I and II, correlates with a greater risk for developing rosacea
[4]. The prevalence of this condition can be as high as 22% in Europe, according to an Estonian study [5], whereas the global
prevalence is estimated in 5.46% in a recently published systematic review [3].
A retrospective study comparing 145 healthy controls and 172 individuals classified either as flushers or diagnosed with
rosacea demonstrated that the “cases” had significantly higher chance to have lower skin phototypes (OR 1.75; 95% CI 1.01-
3.04; P <0.05) [6]. A large observational study conducted in the UK demonstrated a higher incidence of rosacea in the North
of the country, even after age standardisation. This is in accordance with the global trend, as the Irish population is
predominantly light-skinned [7]. Another investigation comparing the prevalence of skin diseases in Ghana and the UK
demonstrated a prevalence of rosacea of 0% in Ghana, in a significant contrast with the rate of 1.80% found in the UK. This | June-2020
result marks different prevalences in northern versus southern countries explained by genetic or climatic influences, or maybe
justified by the diagnosis insensitivity in dark-skinned subjects [4,8].
2.2. Rosacea in people with skin of colour
Rosacea has been always considered a disease of fair-skinned people, leading to the erroneous perception that this disorder
does not occur in people with skin of colour. This point of view is being reconsidered as many reports have shown that
people of any racial or ethnic group can be afflicted with rosacea. The estimates of rosacea prevalence in people with higher
skin phototypes are quite variable. In African, Asian, Hispanic and Indigenous populations, the higher density of skin
pigment masking the facial erythema, in combination with the protective effect of melanin against UV radiation, could
explain the lower prevalence of rosacea with darker skin phototypes [1]. The obvious difficulties in recognising telangiectasia
and erythema in people with skin of colour increase the chances of under-reporting rosacea in these populations [4].
A large retrospective study that assessed the medical records of nearly 6,700 black African patients, over a period of 8 years,
found a very low prevalence of rosacea (0.2%) [9]. In Colombia, where the population comprises a mix of Indigenous,
Hispanic and African ethnicities, the overall rosacea prevalence was estimated in 2.85%, which is considerably different from
the higher rates found in Europe [10].
According to a robust US ambulatory medical care survey, only 2% of rosacea patients were black, 3.9% were
Latino/Hispanic, and 2.3% were Asian. Also in this study, rosacea was considered a primary diagnosis in 2% of whites
compared to 0.6% of blacks presenting with skin rash, in 3% of whites and 0% of blacks reporting abnormal skin
pigmentation, and in 8.3% of whites compared to only 2.2% of blacks complaining of “other diseases of the skin” [11]. These
findings corroborate the postulated higher prevalence of the disease in the fair-skinned population. Similarly, in a nationwide
Japanese muticenter study consisting of 67,448 dermatological patients, the diagnosis of rosacea was found in only 150
patients - a quite low prevalence of 0.22%, comparable to what was found by Dlova & Mosan [9], in black populations [12].
3. Pathogenesis and Natural History: Environment versus Genetics
Following the literature review on rosacea epidemiology, a pertinent question comes up to our minds: is rosacea more
common in fair-skinned individuals because of genetic factors present in Caucasian populations, or because of the colder
temperatures found in the northern areas, especially in Europe? A simplistic way to answer this question would be that, most
likely, both mechanisms in conjunction play a role in the pathogenesis and natural history of this condition.
Is it possible, in the light of the available evidence, to separate and quantify the impact from genetics (including ethnicity)
and environmental factors on the development of the disease? Initially, we have to describe a phenomenon known as cold-
induced vasodilation (CIVD) or the hunting reflex. This refers to a paradoxical vasodilatation that often occurs in the acral
areas to modulate the effects of vasoconstriction, which is, in its turn, the first body response to cold [13,14]. Indeed, people
living in cold regions often have a stronger CIVD reaction in the peripheral vessels, in comparison to those living in warm or
tropical countries. It is presumed that CIVD plays a protective role maintaining tissue integrity and reducing the risks of cold
injury. The physiological mechanisms involved in the CIVD reaction remain largely unclear, despite more than 75 years of | June-2020
research. Such mechanisms may include a simple neuronal reflex, circulating vasodilating substances, disturbances in the
neural transmission between sympathetic neurons and the vascular system, and a potential direct effect of cold on vascular
smooth muscle activity [13].
The natural history of rosacea involves vasodilation caused by various stimuli including the chronic exposure to cold
weather. Persistent vasodilation provokes episodes of flushing, which result in progressive endothelial damage and
neoangiogenesis. The chronic inflammation leads to an increased production of vasoactive substances in the dermis, thus
potentiating vasodilation and again the inflammatory cascade. Inflammation creates a favourable environment for secondary
infection by Demodex microorganisms, especially the folliculorum species, which are responsible for the development of
papulo-pustular and granulomatous lesions [15].
In addition to the influence of the cold weather on rosacea’s pathogenesis, several researches have demonstrated the
important role of UV radiation and photo damage as triggers for this disease. UV light exposure and extreme climatic
conditions induce the production of free radicals in the skin and contribute to the vascular abnormalities observed in rosacea,
i.e., vasodilation, increased capillary permeability, and edema [15].
The existence of a genetic component in rosacea’s etiopathogenesis is confirmed by the demonstration of a remarkable
familial inheritance for the disease. In 2010, Abram et al. observed that patients diagnosed with rosacea had a higher
tendency to exhibit a positive family history to this disorder than did skin-healthy controls (OR 4.31, 95% CI 2.34-7.92,
P<0.0001) [6]. It is also interesting to compare the family history between patients with higher versus lower skin phototypes.
A Saudi study revealed that approximately 30% of rosacea patients classified as phototypes I and II reported a positive family
history, in contrast to only 18% with phototypes IV to VI [16].
In a recent American genome-wide association study including 22,952 individuals of European descent, two single
nucleotide polymorphisms (SNPs), the rs763035 and the rs111314066, were identified to be associated with rosacea [17]. In
the same study, three major histocompatibility complex (MHC) class II proteins, the human leukocyte antigen (HLA)-DRB1,
HLA-DQB1 and HLA-DQA1 were also confirmed to be genetically linked to rosacea. Interestingly, these rosacea-associated
HLA genes have been previously identified to be associated with a variety of autoimmune diseases, such as type 1 diabetes
mellitus and celiac disease [18].
In a review article, Melnik [19], postulated that rosacea evolved as a mutation in Celts to protect them against life-threatening
microbial infections during the Nordic winters. The overexpression of cathelicidin antimicrobial peptide (CAMP) as a
response to an upregulated endoplasmic reticulum stress has been shown to play an important role in rosacea pathogenesis.
The presence of adequate levels of this antimicrobial peptide provides defense against methicillin-resistant Staphylococcus
aureus and mycobacterial infections. The insufficient vitamin D-dependent CAMP activation might have been compensated
by a mutation that activates an alternative vitamin D-independent CAMP promoter, according to this author.
Epidemiological studies of twins are considered important tools to ascertain the role and the weight of genetic versus
environmental factors as etiologic factors for medical conditions. Through the analysis of pre-determined traits in pairs of
identical versus fraternal twins, researchers can quantitatively estimate the genetic and the environmental contributions to a
certain disease. In a large cohort study of 550 American twin individuals, the authors found a significantly higher correlation | June-2020
of the rosacea diagnostic scores between identical twin pairs (r = 0.69), in comparison to fraternal twin pairs (r = 0.46, P =
.04). Statistical analysis revealed a genetic contribution of approximately 46% to the studied phenotype - the remaining 54%
predisposition was accounted for by environmental factors. Among the environmental risk factors, the authors found
significant positive correlations between rosacea and UV exposure, age, body mass index (BMI), smoking, alcohol, cardiac
comorbidity and history of skin cancer. The single most important environmental variable was UV radiation, according to
this study [20].
In the same line of research, Zaidi et al. investigated the facial bacterial microbiome in pair of twins discordant for rosacea
[21]. They found a positive relationship between disease’s severity and colonisation with Gordonia species, and a negative
association between severity and the presence of Geobacillus. For monozygotic twin pairs, such differences may reflect an
important role of environmental contributors to rosacea, most importantly the levels of Demodex mites in the skin. For
fraternal pairs, overlapping genetic factors should also be considered, including the host immune variables and the local
production of antimicrobial peptides.
4. Conclusion
Is rosacea more common in fair-skinned individuals because of genetic factors present in Caucasian populations, or because
of the colder temperatures found in the northern regions of the globe, especially in Europe? The answer to this question may
not be as simple as one could expect. Rosacea etiopathogenesis is complex and multifactorial. Sun-sensitive skin is only one
among many other predisposing factors that include biological elements (immunologic dysregulation, skin colonisation with
Demodex mites) and environmental triggers (ultra-violet radiation, alcohol consumption, cold, heat and physical activity). A
positive family history of rosacea is frequently reported by affected individuals, especially in fair-skinned populations. This
provides a formal proof for a genetic contribution to this disease.
On the one hand, cold-induced vasodilation provokes flushing, endothelial damage and neoangiogenesis. The inflammatory
cascade that takes place in the skin creates a favourable environment for secondary infection by Demodex mites. On the other
hand, recent genetic studies have identified single nucleotide polymorphisms and major histocompatibility complex (MHC)
class II proteins associated with rosacea, in patients of European descent. Genetic mutations in Celtic populations resultant
from the need of protection against life-threatening microbial infections during UV-deficient Nordic winters may also play a
key role in rosacea pathogenesis.
We also highlighted that in people with skin of colour, the denser pigmentation impairs the recognition of erythema and
telangiectasia. This statement leads to at least three other questions:
1. Can the lower rosacea prevalence in populations with higher skin phototypes be attributed to genetic factors?
2. What is the role of the climate in the rosacea epidemiology in such populations?
3. May these findings simply reflect a diagnostic inaccuracy?
Unfortunately, these questions remain unanswered up to this moment, on the basis of the current evidence. The assessment of
the facial microbiome, as a reflect of both genetic and environmental contributing factors, in patients with or without rosacea, | June-2020
in particular siblings, has been proven to be a powerful tool to elucidate the intricate pathogenesis of this condition, and the
differences in its prevalence worldwide.
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2. Holmes AD, Steinhoff M. Integrative concepts of rosacea pathophysiology, clinical presentation and new
therapeutics. Exp Dermatol. 2017;26(8):659-67.
3. Gether L, Overgaard L, Egeberg A, et al. Incidence and prevalence of rosacea: a systematic review and meta-
analysis. Br J Dermatol. 2018;179(2):282-9.
4. Alexis A, Callender V, Baldwin H, et al. Global epidemiology and clinical spectrum of rosacea, highlighting skin of
color: Review and clinical practice experience. J Am Acad Dermatol. 2019;80(6):1722-29.e7.
5. Abram K, Silm H, Oona M. Prevalence of Rosacea in an Estonian Working Population Using a Standard
Classification. Acta DermVenereol. 2010;90(3):269-73.
6. Abram K, Silm H, Maaroos H, et al. Risk factors associated with rosacea. J Eur Acad Dermatol Venereol.
7. Spoendlin J, Voegel J, Jick S, et al. A study on the epidemiology of rosacea in the U.K. Br J Dermatol.
8. Doe P, Asiedu A, Acheampong J, et al. Skin diseases in Ghana and the UK. Int J Dermatol. 2001;40(5):323-6.
9. Dlova N, Mosam A. Rosacea in black South Africans with skin phototypes V and VI. Clin Exp Dermatol.
10. Rueda L, Motta A, Pabón J, et al. Epidemiology of rosacea in Colombia. Int J Dermatol. 2017;56(5):510-3.
11. Al-Dabagh A, Davis SA, McMichael AJ, et al. Rosacea in skin of color: not a rare diagnosis. Dermatol Online J.
12. Furue M, Yamazaki S, Jimbow K, et al. Prevalence of dermatological disorders in Japan: A nationwide, cross-
sectional, seasonal, multicenter, hospital-based study. J Dermatol. 2011;38(4):310-20.
13. Cheung S. Responses of the hands and feet to cold exposure. Temperature (Austin). 2015;2(1):105-20.
14. Castellani J, Young A. Human physiological responses to cold exposure: Acute responses and acclimatization to
prolonged exposure. AutonNeurosci. 2016;196:63-74.
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16. Al Balbeesi AO, Halawani MR. Unusual features of rosacea in saudi females with dark skin. Ochsner J.
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Dermatol. 2016;74(4):667-72.
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DermVenereol. 2016;96(2):147-56. | June-2020
20. Aldrich N, Gerstenblith M, Fu P, et al. Genetic vs Environmental Factors That Correlate with Rosacea. JAMA
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ResearchGate has not been able to resolve any citations for this publication.
Full-text available
Among individuals with skin of color, rosacea has been reported less frequently than in those with white skin, but it is not a rare disease. In fact, rosacea may be underreported and underdiagnosed in populations with skin of color because of the difficulty of discerning erythema and telangiectasia in dark skin, as well as underestimation of the susceptibility of more highly pigmented skin to dermatologic conditions like rosacea whose triggers include sun exposure. Many people with skin of color who have rosacea may experience delayed diagnosis leading to inappropriate or inadequate treatment, greater morbidity, and uncontrolled, progressive disease with disfiguring manifestations, including phymatous rosacea. This paper reviews the epidemiology of rosacea in skin of color and highlights variations in the clinical presentation of rosacea across the diverse spectrum of patient populations affected. It presents strategies to aid in the timely diagnosis and effective treatment of rosacea in patients with skin of color, with an aim of promoting increased awareness of rosacea in these patients and reducing disparities in the management of their disease.
Full-text available
Previously, we determined that genetic and environmental factors contributed equally towards rosacea in twins. To assess an environmental factor, we characterized the malar cheek bacterial microbiome from twins discordant for rosacea. We found no significant difference in facial microbiome alpha and beta diversity between related twins discordant for rosacea. However, the relative percentage abundance of Gordonia and Geobacillus, low abundant genera, was positively and negatively associated with rosacea severity, respectively. Our data demonstrate a significant correlation between facial microbiome and severity of rosacea in genetically matched twins and importantly that overall microbiome composition is largely unchanged.
Full-text available
Rosacea is a chronic relapsing inflammatory skin disease with a high prevalence among adults of Northern European heritage with fair skin. Symptoms present in various combinations and severity, often fluctuating between periods of exacerbation and remission. Based on morphological characteristics, rosacea is generally classified into four major subtypes: erythematotelangiectatic, papulopustular, phymatous, and ocular. Diverse environmental and endogenous factors have been shown to stimulate an augmented innate immune response and neurovascular dysregulation; however, rosacea's exact pathogenesis is still unclear. An evidence-based approach is essential in delineating differences between the many available treatments. Because of the diverse presentations of rosacea, approaches to treatment must be individualized based on the disease severity, quality-of-life implications, comorbidities, trigger factors, and the patient's commitment to therapy.
Full-text available
Cold exposure in humans causes specific acute and chronic physiological responses. This paper will review both the acute and long-term physiological responses and external factors that impact these physiological responses. Acute physiological responses to cold exposure include cutaneous vasoconstriction and shivering thermogenesis which, respectively, decrease heat loss and increase metabolic heat production. Vasoconstriction is elicited through reflex and local cooling. In combination, vasoconstriction and shivering operate to maintain thermal balance when the body is losing heat. Factors (anthropometry, sex, race, fitness, thermoregulatory fatigue) that influence the acute physiological responses to cold exposure are also reviewed. The physiological responses to chronic cold exposure, also known as cold acclimation/acclimatization, are also presented. Three primary patterns of cold acclimatization have been observed, a) habituation, b) metabolic adjustment, and c) insulative adjustment. Habituation is characterized by physiological adjustments in which the response is attenuated compared to an unacclimatized state. Metabolic acclimatization is characterized by an increased thermogenesis, whereas insulative acclimatization is characterized by enhancing the mechanisms that conserve body heat. The pattern of acclimatization is dependent on changes in skin and core temperature and the exposure duration.
Full-text available
Increased expression of cathelicidin antimicrobial peptide (CAMP) is related to the pathogenesis of rosacea. CAMP plays a crucial role in antimicrobial defences, such as the killing of mycobacteria. CAMP gene expression is regulated by vitamin D-dependent (VDR) and vitamin D-independent (C/EBPα) transcription factors. VDR-dependent CAMP expression is sufficient during the summer months in Nordic countries, but insufficient during Nordic winters, due to low ultraviolet (UV) levels. Historically, the Celts may have overcome this geographical disadvantage of deficient CAMP production during the winter through an as-yet undefined acquired mutation that activates the alternative vitamin D-independent CAMP promoter C/EBPα. C/EBPα is the downstream transcription factor of Toll-like receptor (TLR)-mediated innate immune reactions and endoplasmic reticulum (ER) stress responses. At the molecular level, all clinical trigger factors for rosacea can be regarded as ER stressors. A mutation-based upregulation of ER stress responsiveness in rosacea may thus explain patients' reduced threshold for ER stressors. It is notable that ER stress upregulates the potent lipid-mediator sphingosine-1-phosphate (S1P), which explains multiple pathological aberrations observed in rosacea skin. Enhanced ER stress/S1P signalling in rosacea appears to compensate for insufficient VDR-dependent CAMP expression, maintaining adequate CAMP levels during UV-deficient winter to combat life-threatening microbial infections, such as Lupus vulgaris. Therefore, rosacea should not be considered as a disadvantage, but as evolution's blessing from the Celts which improved their survival. The concept presented here also explains the mechanism of Finsen's UV-treatment of lupus vulgaris by UV- and ER stress-mediated upregulation of CAMP expression. Rosacea could therefore be described as the Celts' "inborn Finsen lamp".
Background: The exact prevalence and incidence of rosacea remain unknown, although it is a common condition associated with severe non-cutaneous diseases. We performed a systematic review of published literature to examine the global incidence and prevalence of rosacea. Methods: A systematic review of population-based studies reporting the incidence and/or prevalence of rosacea was performed using three electronic medical databases, PubMed, EMBASE, and Web of Science. Data were extracted, and a proportion meta-analysis was performed to obtain pooled proportions. Results: A total of 32 studies were included examining a total of 41 populations with 26,519,836 individuals. 22 populations were from Europe, three from Africa, four from Asia, nine from North America, and three from South America. The pooled proportion of rosacea was 5.46% (95% CI 4.91-6.04) in the general population and 2.39% (95% CI 1.56-3.39) among dermatology outpatients. Self-reported rosacea gave higher prevalence estimates than rosacea diagnosed by clinical examination, suggesting a low specificity of questionnaires based on symptoms. Rosacea affected both women (5.41%, (CI 95% 3.85-7.23)) and men (3.90% (CI 95% 3.04-4.87)), and mostly those aged 45-60 years. Conclusion: We estimated the global prevalence of rosacea based on published data and found that 5.46% of the adult population is affected. However, the prevalence of rosacea depended on the diagnostic method with higher estimates in questionnaire studies and lower estimates in health registries. This article is protected by copyright. All rights reserved.
Rosacea is a chronic facial dermatosis considered to affect primarily white patients with light phototype skin, and is poorly documented in black patients. The aim of this study was to document the clinical features of rosacea in patients with phototypes V and VI. An 8-year retrospective chart review of patients with a clinical and histological diagnosis of rosacea or acne rosacea was undertaken. Of 6700 patients, 15 (0.2%) had rosacea. All were of African descent with skin phototype V or VI. Mean age was 47 years, and female : male ratio was 14 : 1. Of the 15 patients, 5 (33%) were positive for human immunodeficiency virus; 5 (33%) had used topical steroids to treat the roseacea; 6 (40%) had phototype V and presented with erythema, telangiectasia and erythematous papules, while 9 (60%) had phototype VI skin and presented with skin-coloured papules; and 10 (67%) had histology showing granulomatous rosacea, while 5 (33%) declined a facial skin biopsy. A high index of suspicion is required to diagnose rosacea in black patients as the classic signs of erythema and telangiectasia are difficult to discern.
Background: Prevalence of rosacea has been estimated around the world in the range of 0-22%. In Colombia, the prevalence of rosacea remains unknown. The aim of this study was to determine the prevalence of rosacea and the frequencies of its subtypes in Colombia. Methods: This cross-sectional, multicenter study was conducted in six outpatient dermatology clinics across Colombia. A total of 33 dermatologists conducted a comprehensive medical history and physical examination for all rosacea patients seen at their offices over the course of 2 months. All patients who accepted to participate were encouraged to answer a survey about the history of their illness. Results: Of 10,204 outpatients evaluated for rosacea between July and August 2014, 291 rosacea patients were included in this study. The prevalence of rosacea subtypes in this cohort was: 45.3% erythematotelangiectatic (ETR) (n = 132), 48.7% papulopustular (PPR) (n = 142), 4.8% phymatous (n = 14), and 1% ocular (n = 3). Conclusions: Overall, the prevalence in Colombia was 2.85%. Our data represent an important first step to understanding the current state of rosacea in Colombia. The prevalence of rosacea in Colombia is the highest in Latin America among a few reports published, which might be explained by geographic features. However, contrary to our expectations, the prevalence is lower than that in some European countries. We postulate that this finding may be due to methodological differences.
Rosacea is a chronic relapsing inflammatory skin disease with high prevalence world-wide. Recent research suggests that dysregulation of innate and adaptive immune pathways as well as neuro-vascular changes are present, with different degrees of importance in the various subtypes. Neither the etiology, genetics, nor pathophysiological basis of the vascular, inflammatory or fibrotic changes are well understood. The clinical spectrum comprises a huge variability from erythema (vasodilation) to papules/pustules (inflammatory infiltrate) to phymata (fibrosis, glandular hyperplasia) making it a valuable human disease model to understand the interplay between the neurovascular and immune systems as well as the progression from chronic inflammation to fibrosis in skin. The lack of appropriate animal models emphasizes the importance of further translational research validating observed molecular pathways under disease conditions. A wide spectrum of physical (UV, temperature), biological (microbiota, food) and endogenous (genetic, stress) stimuli have been discussed as 'trigger factors' of rosacea. Novel findings implicate keratinocytes, smooth muscle cells, endothelial cells, macrophages, mast cells, fibroblasts, Th1/Th17 cells, antibody-producing B cells, and neurons in the pathobiology of rosacea. So far, pattern recognition receptors like TLR2, transient receptor potential ion channels (TRPV1, TRPA1), cytokines, chemokines, and proteases have been implicated as critical receptors/mediators. However, our understanding of the interactive networks on the molecular level is very limited. Identification of critical molecular components of the inflammatory cascade including antimicrobial peptides, the IL-1β inflammasome, TNF, IFNγ, proteases, and neuropeptides may provide the basis for novel pathomechanism-based therapeutic approaches for this frequent and bothersome skin disease. This article is protected by copyright. All rights reserved.
Background: Rosacea is a common inflammatory skin condition that shares genetic risk loci with autoimmune diseases such as type 1 diabetes mellitus (T1DM) and celiac disease. A recent genomewide association study identified 90 genetic regions associated with T1DM, celiac disease, multiple sclerosis, and/or rheumatoid arthritis, respectively. However, a possible association with rosacea was not investigated. Objective: We evaluated the association between rosacea and T1DM, celiac disease, multiple sclerosis, and rheumatoid arthritis, respectively. Methods: We performed a population-based case-control study. A total of 6759 patients with rosacea were identified and matched with 33,795 control subjects on age, sex, and calendar time. We used conditional logistic regression to calculate crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs). Results: After adjustment for smoking and socioeconomic status, patients with rosacea had significantly increased ORs for T1DM (OR 2.59, 95% CI 1.41-4.73), celiac disease (OR 2.03, 95% CI 1.35-3.07), multiple sclerosis (OR 1.65, 95% CI 1.20-2.28), and rheumatoid arthritis (OR 2.14, 95% CI 1.82-2.52). The association was mainly observed in women. Limitations: We were unable to distinguish between the different subtypes and severities of rosacea. Conclusions: Rosacea is associated with T1DM, celiac disease, multiple sclerosis, and rheumatoid arthritis, respectively, in women, whereas the association in men only reached statistical significance for rheumatoid arthritis.