Oculocutaneous albinism in sub-Saharan Africa: adverse sun-associated health effects and photoprotection

The degradation of TYR variants derived from Chinese OCA families is mediated by the ERAD and ERLAD pathway

Oculocutaneous albinism (OCA) is a genetically heterogeneous group of autosomal recessive disorders, which presents with decreased or absent pigmentation in the hair, skin, and eyes. OCA1, as a subtype of OCA, is caused by mutations in the tyrosinase gene (TYR). In this study, we performed in vitro functional analysis of eight TYR variants (one frameshift variant: c.929dupC (p.Arg311Lysfs*7); seven missense variants: c.896G>A (p.Arg299His), c.1234C>A (p.Pro412Thr), c.1169A>G (p.His390Arg), c.937C>A (p.Pro313Thr), c.636A>T (p.Arg212Ser), c.623 T>G (p.Leu208Arg), c.1325C>A (p.Ser442Tyr)) identified in Chinese OCA families. TYR plasmids were transfected into HEK 293 T cells to explore the effects of TYR variants on their processing, protein expression, activity, and degradation. The results showed that all eight variants caused TYR to be retained in the endoplasmic reticulum (ER), processing was blocked, and TYR activity almost disappeared; the frameshift variant caused the size of the TYR protein to be reduced by about 30KD, and the protein expression of the remaining seven missense variants was reduced; the ER-associated degradation (ERAD) pathway mediates the degradation of TYR variants that occur on the Tyrosinase copper-binding domain, while the degradation of TYR variants that are not located on that domain may be mediated by a new degradation pathway--ER-to-lysosome-associated degradation (ERLAD). In summary, TYR variants affected their protein processing and activity, and may also induce ER stress and trigger degradation through the ERLAD pathway in addition to the ERAD degradation pathway, providing new insights into the potential pathogenic mechanism for OCA1 caused by TYR variants.

Integrated sun protection advice for the South African population

Exposure to solar ultraviolet radiation (UVR) is associated with several cutaneous adverse effects. However, to the best of our knowledge, in South Africa there are no formal guidelines on sun protection. A group of South African dermatologists and researchers convened over the course of 1 year to deliberate on integrated advice for sun protection among the multi-ethnic South African population. For people with light skin and those with genetic skin disorders (e.g., oculocutaneous albinism), sun protection was identified as critical to prevent sunburn, skin cancer, and photoaging. The evidence is less clear for people with medium and darker skin types, especially the latter, in whom melanin may confer a degree of protection against some parts of the solar spectrum. Recent studies have demonstrated that visible light can cause pigmentary changes in individuals with darker skin types in particular. Sun protection for people of all skin colors is beneficial to protect against photoaging and ocular damage. Herein sun protection advice is suggested for South Africans of all skin colors to reduce morbidity and mortality from sun exposure, particularly relating to skin cancer. Several knowledge gaps are identified as future research priorities.

Mapping a research-advocacy-policy agenda on human rights and albinism: a mixed methods project

BACKGROUND

Persons with albinism face challenges to their wellbeing, safety, and security, ranging from vision impairment and skin cancer to stigma and discrimination. In some regions, they also face human rights atrocities including mutilation and murder. Research on human rights and albinism is a relatively new field that has gained momentum since the United Nations appointment of an Independent Expert on the enjoyment of human rights by persons with albinism. In this paper, we present the results of a mixed methods study undertaken to identify priorities for research, advocacy, and policy on albinism and human rights.

METHODS

The first component was a synthesis of peer-reviewed and grey literatures at the nexus of albinism, spiritual/cultural beliefs and practices, and human rights. We then conducted a priority-setting survey, informed by Delphi methods, on extant knowledge-practice gaps and research, advocacy, and policy priorities. Inclusion criteria included demonstrated expertise in the field (e.g., peer-reviewed publications, funded research), membership on national or international associations, or advocacy (civil society organizations) of more than 2 years in albinism and human rights. Thereafter, we gathered leading researchers, policy-makers, and civil society stakeholders for a Roundtable to gain consensus on these priorities.

RESULTS

Access to skin and vision care, and education were not deemed high priority for research, likely because the evidence supporting the need for these is well established. However, they were priorities for advocacy and policy: what is needed is mobilization of this evidence through advocacy and implementation of such services (policy). Other social determinants of health (rurality, poverty, and gender equality) are present as subtext in the findings, more so than priorities for research, advocacy, or policy, despite their preponderance in the lives of persons with albinism. Research was prioritized on stigma and discrimination; advocacy; and witchcraft, but with some differentiation between Global North and Global South priorities. Priorities for research, advocacy, and policy vary in keeping with the explanatory frameworks at play, including how harmful practices and witchcraft are viewed.

CONCLUSIONS

The lived experience of albinism is profoundly shaped by the social determinants of health (SDOH). Threats to the security and well-being of persons with albinism should be viewed through a human rights lens that encompasses the explanatory frameworks at play.

Solar Ultraviolet Radiation, Skin Cancer and Photoprotective Strategies in South Africa†

The most recent data relating to the incidence of, and mortality from, the three commonest forms of skin cancer, namely basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and cutaneous melanoma (CM), in the Black African, Colored, Asian/Indian and White population groups in South Africa are reviewed. While exposure to solar ultraviolet radiation is the major environmental risk factor for BCC in all four groups, for SSC in the White and Asian/Indian groups and for CM in the White group, this is unlikely to be the case for most SCCs in the Black African group and for most CMs in the Black African and Asian/Indian groups. Strategies for practical personal photoprotection in South Africa are discussed with particular emphasis on people at heightened risk of skin cancer including the White population group, those with HIV or oculocutaneous albinism and outdoor workers.

Identification of novel variations of oculocutaneous albinism type 2 with Prader-Willi syndrome/Angelman syndrome in two Chinese families

Objective: Oculocutaneous albinism (OCA) is an autosomal recessive disorder caused by a variety of genomic variations. Our aim is to identify the molecular basis of OCA in two families and lay the foundation for prenatal diagnosis. Methods: Four types of OCA-causing mutations in the TYR, p, TYRP1, or SLC45A2 genes were screened. Linkage analysis was performed because the mutations found in the p gene violated the laws of classical Mendelian heredity. Primer-walking sequencing combined with microsatellite and single-nucleotide polymorphism analysis was used to ascertain deletion ranges. Bioinformatics methods were used to assess the pathogenicity of the new mutations. Results: Proband 1 was diagnosed as OCA2 with Prader-Willi syndrome (PWS) due to a novel atypical paternal deletion (chromosome 15: 22330347-26089649) and a pathogenic mutation, c.1327G>A (Val443Ile), in the p gene of the maternal chromosome. The prenatal diagnosis results for family 1 indicated the fetus was a heterozygous carrier (c.1327G>A in the p gene) with a normal phenotype. Proband 2 was diagnosed as OCA2 with Angelman syndrome (AS) due to a typical maternal deletion of chromosome 15q11-q13 and a novel mutation, c.1514T>C (Phe505Ser), in the p gene of the paternal chromosome. This novel mutation c.1514T>C (Phe505Ser) in the p gene was predicted as a pathogenic mutation. Conclusion: Our study has shown clear genotype-phenotype correlations in patients affected by distinct deletions of the PWS or AS region and missense mutations in the p gene. Our results have enriched the mutation spectrum of albinism diseases and provided insights for more accurate diagnosis and genetic counseling.

Skin conditions among pediatric dermatology outpatients in Botswana

BACKGROUND

An understanding of the prevalence patterns of skin diseases in children in Botswana is needed to guide national dermatological policy development, training, and resource allocation to improve patient care.

OBJECTIVE

To describe local skin disease patterns in children aged 0-18 years presenting for dermatologic care in Botswana.

METHODS

A retrospective review of records from 1st January 2011 to 31st December 2016 was conducted at the outpatient dermatology clinic of Princess Marina Hospital (PMH) in Gaborone, Botswana and outreach clinic sites.

RESULTS

There were 4413 pediatric visits constituting 18.6% of all dermatology visits. There was a slight male predominance of 1.2:1. The majority of disorders were noninfectious 80.1% (3537/4413) versus infectious 14.6% (645/4413), with 5.2% (231/4413) unclassified. In the noninfectious category, two-thirds were inflammatory, followed by disorders of nails, skin appendages, and pigmentary disorders. Atopic dermatitis was the most common inflammatory disorder. Over half of infectious skin diseases were viral, followed by fungal and bacterial disorders. In the HIV-related disorders, the majority were verrucae 94% (108/115) followed by Kaposi sarcoma. The nine most common skin diagnoses accounted for close to 70% of all skin diseases seen at the clinic, and these included atopic dermatitis (almost half of all cases), followed by verruca, acne, and vitiligo.

CONCLUSION

There is a high burden of skin disorders in children in Botswana. In our cohort, a small number of skin conditions made up the vast majority of pediatric diagnoses. This information can be used to guide dermatology training and resource allocation to better manage these common diseases.

Oculocutaneous albinism in southern Africa: Historical background, genetic, clinical and psychosocial issues

Albinism is an inherited condition associated with significant depigmentation of the skin, hair and eyes. It occurs in every population with varying frequency, and narratives of people with albinism have been recorded since 200 BC. In southern Africa albinism is common, about 1 in 4000 people are affected, but it remains a poorly understood condition surrounded by myths and superstition. This article provides a historical background on oculocutaneous albinism (OCA) in southern Africa and presents relevant information from the literature regarding epidemiology, genetics and genetic counselling, health, psychosocial and cultural issues, and medical care. There are several recessively inherited types of OCA and a mutation, responsible for about 80% of South African variants, has been identified in OCA type 2. The physical characteristics associated with albinism, that is, sun-sensitive skin and low vision, can be managed. However, people with OCA in Africa also experience psychosocial issues, such as discrimination, because of the various superstitious beliefs and attitudes held in the community. Management should include medical care for health problems, appropriate adjustment of the schooling context and genetic counseling. In addition, widespread public awareness programmes are required to increase the knowledge of the genetic causes of OCA and of the nature of genetic counselling, to address the negative attitudes in the community, to reduce the marginalisation and stigmatization of people with albinism and to improve their quality of life.

Dermatologic manifestations in patients with the Hermansky-Pudlak syndrome types 1 and 3

Background

The Hermansky–Pudlak syndrome (HPS) is a genetically heterogeneous group of diseases characterized by oculocutaneous albinism, bleeding diathesis, and systemic complications. It is the most common genetic disorder in Puerto Rico. These patients are at a significant risk of developing a variety of skin complications and little is known about the prevalence of dermatologic diagnoses in this population.

Objectives

To report dermatologic manifestations in patients with Hermansky–Pudlak syndrome (HPS). Secondary aims include skin concerns, sun protection habits, barriers to dermatologic care, and skin cancer knowledge.

Methods

Cross-sectional study with twenty-nine Puerto Rican patients who carried a clinical diagnosis of HPS type 1 or type 3 through a telephonic questionnaire.

Results

Twenty-nine patients participated with a mean (SD) age of 37.3 (16.8) years and the majority were female (69%). The most common diagnoses were skin cancer (34.5%), acne (34.5%), bacterial skin infections (34.5%), warts (24%), urticaria (17.2%), and psoriasis (17.2%). The most common skin concerns were dry skin (62.1%), hair loss (58.9%), redness (34.5%), moles (31%), and rash (31%). The most common sun protection behavior was wearing a shirt that covers the shoulders (93.1%, often or always) and the least common was wearing a hat (24.1%, often or always). Higher income was significantly associated with being more likely to use sunscreen often or always (OR = 3.38, 95% CI 1.02–11.18, p = 0.04). Those in northern urban areas were significantly less likely to report barriers to dermatologic care (OR = 0.13, 95% CI 0.02–0.76, p = 0.02).

Conclusions

This study provides an important overview of the most common self-reported skin manifestations in patients with HPS. Unfortunately, a high prevalence of cutaneous malignancy was reported. The results stress the need for adequate care and potential interventions to promote sun protection behaviors and skin cancer prevention.

Living with albinism in an African community: exploring the challenges of persons with albinism in Lilongwe District, Malawi

BACKGROUND

Albinism is a genetic condition caused by a deficit in the production of the pigment called melanin, which protects the skin against ultraviolet light and provides the skin with its color production. The condition may predispose persons with albinism (PWAs) to lifelong physical and health problems, such as visual impairment and ultra-violet induced skin damage. Due to this condition, we explored the challenges faced by persons living with albinism as they socialize in Lilongwe District, Malawi.

METHOD

The study adopted an interpretative phenomenological approach and included 30 participants comprising 13 females and 14 males with albinism and three key informants from Association of People with Albinism in the Lilongwe district in Malawi. Data were collected through in-depth interviews and focus group discussions. Van Manen's (2014) six steps of phenomenological analysis was used to analyze all data.

RESULTS

People with albinism face a variety of problems, the most common of which are financial constraints, health complications due to a lack of adequate medical care, a lack of community support leading to stigma and discrimination, and superstitious beliefs.

CONCLUSIONS

People with albinism suffer socially as a result of misconceptions, behaviours, social isolation, labelling, and beliefs that are negatively correlated with their disorder. PWAs face these problems as a result of public misunderstanding about albinism.

Sociodemographic features of a cohort of people living with albinism in Botswana

Background

Oculocutaneous albinism is disproportionately prevalent in Africa; however, the medical and psychosocial characteristics of people living with albinism (PWA) in Botswana have not been studied.

Objective

To characterize the demographics, health-related factors, sun-protective behaviors, and psychosocial challenges of PWA in Botswana.

Methods

Overall, 50 PWA and 99 patients without albinism (non-PWA) were recruited and surveyed.

Results

Higher proportions of PWA lived in rural villages compared with non-PWA (odds ratio [OR], 2.59; 95% confidence interval [CI], 1.26-5.34). PWA reported limited access to health care more frequently compared with non-PWA (OR, 2.72; 95% CI, 1.11-6.62). High proportions of PWA adopted sun-protective measures, including sunscreen, clothing, and sunlight avoidance. Despite high rates of feeling accepted by family and peers, PWA had increased odds of feeling unaccepted by their community (OR, 15.16; 95% CI, 5.25-31.81), stigmatized by society (OR, 9.37; 95% CI, 3.43-35.62), and affected by stigma in social interactions (OR, 2.21; 95% CI, 1.08-4.54) compared with non-PWA. Three-quarters of PWA had witnessed mistreatment of PWA.

Limitations

Study limitations include the small sample size, convenience sampling, and a non-validated survey instrument.

Conclusion

PWA faced increased medical and psychosocial challenges compared with non-PWA in Botswana. Our findings can begin to inform public health strategies aimed at promoting improved health care, education, and social inclusion for this population in Botswana and other regions in Africa.

Factors Affecting Quality of Life for People Living with Albinism in Botswana

People with albinism (PWA) in Africa suffer many challenges, including higher risk of skin cancers and deeply embedded stigma. We conducted interviews with PWA to determine factors influencing their quality of life (QOL) in Botswana. Physical concerns expressed included skin/eye health issues and limited access to health care. Psychosocial concerns included stigma/discrimination and myths/superstitions. Environmental concerns included barriers to personal development of education and employment, safety concerns, financial insecurity, and disability rights issues. Pervasive difficulty in obtaining equal rights to physical, psychosocial, and environmental health affected QOL. Education around albinism and disability rights are needed to improve QOL for PWA.

Dermatological and epidemiological profile of patients with albinism in Togo in 2019: results of two consultation campaigns

BACKGROUND

People with albinism (PWA) are targets of prejudice and social exclusion and have limited access to specialized medical care and resources. Our study aimed to describe the epidemiological and dermatological profile of PWA in Togo.

METHOD

We carried out a cross-sectional study of 294 medical records of PWA systematically examined during two mobile skin care clinics in 2019.

RESULTS

The mean age of the patients was 22 ± 16.5 years, and the gender ratio (M/F) was 1. A family history of albinism was reported in 27.9% of cases, and consanguinity between the parents was found in 24.1% of PWA. Dermatological lesions on physical examination were present in 95.2% of PWA. These lesions were elastosis/wrinkles (82.9%), ephelides (79.6%), actinic keratoses (60.0%), actinic cheilitis (50.0%), and cutaneous carcinomas (11.8%). The mean age of PWA with skin carcinomas was 38.6 years. Fifty-four cases of cutaneous carcinomas had been diagnosed (31 cases of basal cell carcinoma, 21 cases of squamous cell carcinoma, and 2 cases of Bowen's disease) and were located mainly in the cephalic region (61.1%) and upper limbs (27.8%). Cryotherapy and/or excisional biopsies were the treatments for premalignant and malignant lesions. All PWA were sensitized on sun protection.

CONCLUSIONS

This study shows the basic picture of dermatological characteristics of PWA with a high frequency of photo-induced lesions and skin cancers. The popularization and respect of photoprotection measures and regular skin examination of these PWA for early detection and management of lesions will reduce their morbidity and mortality.

A Histopathological Study of Skin Lesions in Individuals with Oculocutaneous Albinism in Togo in 2019

Objective

The aim of this study was to study the histopathological patterns of skin lesions in persons with albinism (PWA) in Togo in 2019.

Method

During two mobile skin care clinics in 2019, biopsies/excisional biopsies were performed in PWA in case of clinical doubt or in front of lesions suspected to be cancerous for histological examination. Anatomopathological reports were thus analysed.

Results

During the two mobile skin care clinics, 115 biopsies/excisional biopsies were carried out in 79 PWA, with a mean age of 24 ± 16.1 years. Histological examination led to a diagnosis in 110 cases (95.6%) and was inconclusive in 5 cases (4 cases of uncertain histological diagnosis and one case of nonspecific histological lesions). Fourteen different histological diagnoses were made, with a frequency ranging from 0.9% (one case) to 26.9% (31 cases). The four most frequent diagnoses in descending order were basal cell carcinomas (BCCs) (31 cases; 26.9%), invasive squamous cell carcinomas (SCCs) or Bowen's disease (23 cases; 20%), keratosis (20 cases; 17.3%), and cysts (seven cases; 6.1%). The 54 skin carcinomas were diagnosed in 33 (41.8%) of the 79 patients who underwent skin biopsies/excisional biopsies. The BCC/SCC ratio was 1.3. No cases of cutaneous melanoma had been diagnosed.

Conclusion

Skin cancers represent the main histological diagnosis in PWA (46.9%) in Togo in 2019. The pattern of cutaneous malignancies in PWA shows the same trend as that seen in Caucasians with a predominance of basal cell carcinomas.

The Epidemiology of Skin Cancer and Public Health Strategies for Its Prevention in Southern Africa

Skin cancer is a non-communicable disease that has been underexplored in Africa, including Southern Africa. Exposure to solar ultraviolet radiation (UVR) is an important, potentially modifiable risk factor for skin cancer. The countries which comprise Southern Africa are Botswana, Lesotho, Namibia, South Africa, and Swaziland. They differ in population size and composition and experience different levels of solar UVR. Here, the epidemiology and prevalence of skin cancer in Southern African countries are outlined. Information is provided on skin cancer prevention campaigns in these countries, and evidence sought to support recommendations for skin cancer prevention, especially for people with fair skin, or oculocutaneous albinism or HIV-AIDS who are at the greatest risk. Consideration is given to the possible impacts of climate change on skin cancer in Southern Africa and the need for adaptation and human behavioural change is emphasized.

Review of the Global Solar UV Index 2015 Workshop Report

The Global Solar UV Index was developed as an easy-to-understand measure of the amount of biologically-effective ambient solar ultraviolet radiation (UVR) at different locations on the earth's surface. Over the past few years, questions have been raised about the global applicability of the UV Index, about the evidence base for exposure risk thresholds and related protective measures, and about whether the overall impact of the UV Index could be improved with modifications. An international workshop was organized by several organizations, including the World Health Organization, to assess if current evidence was sufficiently strong to modify the UV Index and to discuss different ways it might be improved in order to influence sun-protective behavior. While some animal research suggests there may be no threshold effect, the relative importance of sub-erythemal doses of sunlight in causing skin cancer in humans remains unknown. Evidence suggests that regular use of sunscreen can prevent skin cancer and that sunglasses are an effective method of protecting the eyes from solar UVR. The UV Index as a risk communication tool continues to be useful for raising awareness and to support sun-protection behavior. Although there was agreement that guidance on the use of the UV Index could be improved, the workshop participants identified that strong health outcome-based human evidence would be needed as the basis for a revision. For the UV Index to be relevant in as many countries as possible, it should continue to be adapted to suit local conditions.

'My child did not like using sun protection': practices and perceptions of child sun protection among rural black African mothers

BACKGROUND

Photodamage is partially mitigated by darker skin pigmentation, but immune suppression, photoaging and cataracts occur among individuals with all skin types.

METHODS

To assess practices and acceptability to Black African mothers of sun protection equipment for their children living in a rural area, participants were recruited at the time of their child's 18-month vaccinations. Mothers completed a baseline questionnaire on usual sun behaviours and sun protection practices. They were then provided with sun protection equipment and advice. A follow-up questionnaire was administered two weeks later.

RESULTS

Mothers reported that during the week prior to the baseline questionnaire, children spent on average less than 1 hour of time outdoors (most often spent in the shade). Most mothers (97%) liked the sun protection equipment. However, many (78 of 86) reported that their child did not like any of the sun protection equipment and two-thirds stated that the sun protection equipment was not easy to use.

CONCLUSIONS

Among Black Africans in rural northern South Africa, we found a mismatch between parental preferences and child acceptance for using sun protection when outdoors. A better understanding of the health risks of incidental excess sun exposure and potential benefits of sun protection is required among Black Africans.

Sun protection to improve vaccine effectiveness in children in a high ambient ultraviolet radiation and rural environment: an intervention study

BACKGROUND

Vaccination is a mainstay of preventive healthcare, reducing the incidence of serious childhood infections. Ecological studies have demonstrated an inverse association between markers of high ambient ultraviolet (UV) radiation exposure (e.g., sunny season, low latitude of residence) and reduction in the vaccination-associated immune response. Higher sun exposure on the day prior to and spanning the day of vaccination has been associated with a reduced antigen-specific immune response independent of skin pigmentation. The South African Department of Health's Expanded Programme on Immunisation provides free vaccinations in government primary health care clinics. In some areas, these clinics may have only a small waiting room and patients wait outside in full sun conditions. In rural areas, patients may walk several kilometres to and from the clinic. We hypothesised that providing sun protection advice and equipment to mothers of children (from 18 months) who were waiting to be vaccinated would result in a more robust immune response for those vaccinated.

METHODS

We conducted an intervention study among 100 children receiving the booster measles vaccination. We randomised clinics to receive (or not) sun protection advice and equipment. At each clinic we recorded basic demographic data on the child and mother/carer participants, their sun exposure patterns, and the acceptability and uptake of the provided sun protection. At 3-4 weeks post-vaccination, we measured measles IgG levels in all children.

DISCUSSION

This is the first intervention study to assess the effect of sun protection measures on vaccine effectiveness in a rural, real-world setting. The novel design and rural setting of the study can contribute much needed evidence to better understand sun exposure and protection, as well as factors determining vaccine effectiveness in rural Africa, and inform the design of immunisation programmes. (TRN PACTCR201611001881114, 24 November 2016, retrospective registration).

The impact of skin colour on human photobiological responses

Terrestrial solar ultraviolet radiation (UVR) exerts both beneficial and adverse effects on human skin. Epidemiological studies show a lower incidence of skin cancer in people with pigmented skins compared to fair skins. This is attributed to photoprotection by epidermal melanin, as is the poorer vitamin D status of those with darker skins. We summarize a wide range of photobiological responses across different skin colours including DNA damage and immunosuppression. Some studies show the generally modest photoprotective properties of melanin, but others show little or no effect. DNA photodamage initiates non‐melanoma skin cancer and is reduced by a factor of about 3 in pigmented skin compared with white skin. This suggests that if such a modest reduction in DNA damage can result in the significantly lower skin cancer incidence in black skin, the use of sunscreen protection might be extremely beneficial for susceptible population. Many contradictory results may be explained by protocol differences, including differences in UVR spectra and exposure protocols. We recommend that skin type comparisons be done with solar‐simulated radiation and standard erythema doses or physical doses (J/m²) rather than those based solely on clinical endpoints such as minimal erythema dose (MED).

Basis for the gain and subsequent dilution of epidermal pigmentation during human evolution: The barrier and metabolic conservation hypotheses revisited

The evolution of human skin pigmentation must address both the initial evolution of intense epidermal pigmentation in hominins, and its subsequent dilution in modern humans. While many authorities believe that epidermal pigmentation evolved to protect against either ultraviolet B (UV-B) irradiation-induced mutagenesis or folic acid photolysis, we hypothesize that pigmentation augmented the epidermal barriers by shifting the UV-B dose-response curve from toxic to beneficial. Whereas erythemogenic UV-B doses produce apoptosis and cell death, suberythemogenic doses benefit permeability and antimicrobial function. Heavily melanized melanocytes acidify the outer epidermis and emit paracrine signals that augment barrier competence. Modern humans, residing in the cooler, wetter climes of south-central Europe and Asia, initially retained substantial pigmentation. While their outdoor lifestyles still permitted sufficient cutaneous vitamin D3 (VD3) synthesis, their marginal nutritional status, coupled with cold-induced caloric needs, selected for moderate pigment reductions that diverted limited nutritional resources towards more urgent priorities (=metabolic conservation). The further pigment-dilution that evolved as humans reached north-central Europe (i.e., northern France, Germany), likely facilitated cutaneous VD3 synthesis, while also supporting ongoing, nutritional requirements. But at still higher European latitudes where little UV-B breaches the atmosphere (i.e., present-day UK, Scandinavia, Baltic States), pigment dilution alone could not suffice. There, other nonpigment-related mutations evolved to facilitate VD3 production; for example, in the epidermal protein, filaggrin, resulting in reduced levels of its distal metabolite, trans-urocanic acid, a potent UV-B chromophore. Thus, changes in human pigmentation reflect a complex interplay between latitude, climate, diet, lifestyle, and shifting metabolic priorities.

Knowledge and practice of sun protection in schools in South Africa where no national sun protection programme exists

Interventions in primary schools that increase sun-protective behaviours and decrease ultraviolet radiation exposure, sunburn incidence and skin cancer risk can be effective. SunSmart School Accreditation Programmes (SSAP) are recommended. Prior to SSAP implementation in South Africa, we explored the feasibility of obtaining national baseline information and investigated possible associations between strategies regarding sun protection in schools and students' responses to a questionnaire. Principals from randomly selected urban government schools in all nine South African provinces completed a questionnaire and 679 students were surveyed. The mean sun-related knowledge and behaviour scores of students were 4 (range: 1-7) and 3 (range-0-8) out of 9, respectively. The mean school sun protection effort score was 4 out of 14. There were no statistically significant correlations between students' knowledge or behaviour scores and their school score. The World Health Organization recommends an SSAP to address policy, practice and curriculum changes to support sun protection of students. This cross-sectional study demonstrates the feasibility of, and need for, a larger baseline study with longitudinal, multi-variable follow-up which includes other influential factors, such as parent support. Such research could quantify the impact of the SSAP and identify which key factors influence the sun-related knowledge and behaviours of students.

Solar ultraviolet radiation in Africa: a systematic review and critical evaluation of the health risks and use of photoprotection

The majority of the African continent experiences high solar UVB radiation throughout the year. The adverse consequences of this on the health of populations living in Africa are reviewed.