Analysis of MC1R variants in Indian oculocutaneous albinism patients: highlighting the risk of skin cancer among albinos

Skin cancers in people with albinism in Togo in 2019: results of two rounds of national mobile skin care clinics

Background

In people with albinism (PWA), the deficiency of melanin increase the risk of skin cancers. The aim of this study was to determine the prevalence of skin cancers and characteristics of these detected skin cancers (histological types, localization) in PWA in 10 cities in Togo in 2019.

Methods

This is a cross-sectional study of medical records of PWA systematically examined during two mobile skin care clinics in 2019, as part of a programme for the prevention and management of skin cancers in these subjects.

Results

During the study period, 280 (95.2%) of the 294 PWA consulted, had developed skin lesions. Of the 280 PWA, the pathological reports from the medical records of 33 patients (11.8%; (95%CI = [8.2–16.2]) had concluded to non-melanoma skin cancers. The mean age of these 33 patients was 38.6 ± 15.2 years and the sex-ratio was 1. Their occupations were mainly resellers (21.2%), traders (15.2%) and farmers (12.2%). In the 33 patients, 54 cases of non-melanoma skin cancers were identified, with some patients having more than one tumor, and some of them having more than one (histologically confirmed) diagnosis. These 54 non-melanoma skin cancers were divided into 21 cases of invasive squamous cell carcinomas, 2 cases of Bowen’s disease and 31 cases of basal cell carcinomas. These non-melanoma skin cancers mainly occurred in the head and neck (33 cases; 61.1%), the upper limbs (15 cases; 27, 8%) and the trunk (4 cases; 7.4%).

Conclusion

The results of this study show a high prevalence of skin cancers among PWAs in Togo in 2019, only non-melanoma skin cancers. In addition, they illustrate the role of ultraviolet rays with regard to the localization of skin cancers and the occupations of patients. Popularization and compliance with photo protection measures, systematic and regular examination of the skin of these PWAs will allow early detection and treatment of these skin cancers.

The long noncoding RNA MALAT1 suppresses miR-211 to confer protection from ultraviolet-mediated DNA damage in vitiligo epidermis by upregulating sirtuin 1

BACKGROUND

The absence of melanocytes poses a challenge for long-term tissue homeostasis in vitiligo. Surprisingly, while individuals with Fitzpatrick phototypes I-II (low melanin content) have a higher incidence of melanoma and nonmelanoma skin cancer, people with vitiligo are at a decreased risk for the same.

OBJECTIVES

To understand the molecular mechanisms that protect vitiligo skin from ultraviolet (UV)-induced DNA damage by (i) characterizing differentially expressed microRNAs in lesional vs. nonlesional epidermis and (ii) identifying their upstream regulators and downstream gene targets.

METHODS

Genome-wide microRNA profiling of nonlesional and lesional epidermis was performed on five individuals with stable nonsegmental vitiligo using next-generation RNA sequencing. The relevance of the upstream regulator and downstream target gene of the most differentially expressed microRNA was studied.

RESULTS

Our study found sirtuin1 (SIRT1), an NAD-dependent deacetylase, to be a direct target of miR-211 - the most significantly downregulated microRNA in lesional epidermis. Inhibition of SIRT1 with EX-527 downregulated keratin 10 and involucrin, suggesting that SIRT1 promotes keratinocyte differentiation. Overexpression of miR-211 mimic led to a significant increase in γ-H2AX positivity and cyclobutane pyrimidine dimer (CPD) formation, hallmarks of UVB-mediated DNA damage. These effects could be ameliorated by the addition of resveratrol, a SIRT1 activator. Furthermore, a long noncoding RNA, MALAT1, was identified as a negative upstream regulator of miR-211. Overexpression of MALAT1 resulted in increased expression of SIRT1 and a concomitant removal of UVB-induced CPDs in primary keratinocytes.

CONCLUSIONS

These findings establish a novel MALAT1-miR-211-SIRT1 signalling axis that potentially confers protection to the 'amelanotic' keratinocytes in vitiligo.

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.

Mapping the TYR gene reveals novel and previously reported variants in Eastern Indian patients highlighting preponderance of the same changes in multiple unrelated ethnicities

Oculocutaneous albinism (OCA) is a group of congenital autosomal recessive disorders with seven known subtypes (OCA1-OCA7) characterized by loss or absence of pigmentation in the skin, hair, and eyes. OCA1, caused by pathogenic variations in the tyrosinase (TYR) gene, has been documented to be the most prevalent subtype across the world including India. In the present study, we recruited 53 OCA-affected individuals from 45 unrelated families belonging to 20 different marriage groups/ethnicities of 15 different districts of West Bengal. We took a targeted sequencing-based approach to find the causal variations in the TYR gene. We report here identification of two novel potentially pathogenic variations [NM_000372.4:c.614C>T, NP_000363.1:p.(Pro205Leu), and NM_000372.4:c.1036+1=/G>T], one novel synonymous TYR variant [NM_000372.4:c.204=/A>G, NP_000363.1:p.(Gln68=)], two pathogenic variations documented for the first time in Indian OCA cases [NM_000372.4:c.1147G>A, NP_000363.1:p.(Asp383Asn), and NM_000372.4:c.585G>A, NP_000363.1:p.(Trp195*)], along with nine previously reported pathogenic variants in 36 out of 53 (∼68%) patients recruited. We report common haplotype backgrounds for the two most prevalent variations [NM_000372.4:c.124G>A, NM_000372.4:c.832C>T] in cases belonging to different marriage/ethnic groups, suggesting a possible founder effect. To our knowledge, this is the most comprehensive genetic study on OCA1 from India, firmly establishing OCA1 as the commonest form of albinism in this part of the world.

Albinism: epidemiology, genetics, cutaneous characterization, psychosocial factors

Oculocutaneous albinism is an autosomal recessive disease caused by the complete absence or decrease of melanin biosynthesis in melanocytes. Due to the reduction or absence of melanin, albinos are highly susceptible to the harmful effects of ultraviolet radiation and are at increased risk of actinic damage and skin cancer. In Brazil, as in other parts of the world, albinism remains a little known disorder, both in relation to epidemiological data and to phenotypic and genotypic variation. In several regions of the country, individuals with albinism have no access to resources or specialized medical care, and are often neglected and deprived of social inclusion. Brazil is a tropical country, with a high incidence of solar radiation during the year nationwide. Consequently, actinic damage and skin cancer occur early and have a high incidence in this population, often leading to premature death. Skin monitoring of these patients and immediate therapeutic interventions have a positive impact in reducing the morbidity and mortality associated with this condition. Health education is important to inform albinos and their families, the general population, educators, medical professionals, and public agencies about the particularities of this genetic condition. The aim of this article is to present a review of the epidemiological, clinical, genetic, and psychosocial characteristics of albinism, with a focus in skin changes caused by this rare pigmentation disorder.

Oculocutaneous Albinism and Squamous Cell Carcinoma of the Skin of the Head and Neck in Sub-Saharan Africa

Oculocutaneous albinism which is characterised by impaired melanin biosynthesis is the most common inherited pigmentary disorder of the skin and it is common among Blacks in sub-Saharan Africa. All albinos are at great risk of developing squamous cell carcinoma of sun-exposed skin, and Black albinos in sub-Saharan Africa are at about a 1000-fold higher risk of developing squamous cell carcinoma of the skin than the general population. In Black albinos, skin carcinoma tends to run an aggressive course and is likely to recur after treatment, very probably because the aetiology and predisposing factors have not changed. Prevention or reduction of occurrence of squamous cell carcinoma of the skin in Black albinos might be achieved through educating the population to increase awareness of the harmful effects of exposure to sunlight and at the same time making available effective screening programs for early detection of premalignant and malignant skin lesions in schools and communities and for early treatment.

Dermatological disorders in Tuvalu between 2009 and 2012

There is a distinct lack of knowledge on the prevalence of skin disorders in Tuvalu. The aim of the current study was to assess the prevalence of cutaneous diseases and to evaluate access dermatological care in Tuvalu. Cutaneous disorders in the people of Tuvalu between 2009 and 2012 were examined. The most common skin conditions were eczema/dermatitis, superficial fungal infections, impetigo, carbuncles, furuncles, folliculitis, acne, scabies, warts and keloids. Infrequent skin conditions included infectious granulomatous disease, albinism, actinic keratosis, skin cancer, cutaneous lupus erythematosus and mammary Paget's disease, which required medical attention. This is the first epidemiological report on skin disorders in the southwest Pacific Island, Tuvalu.

Relationship between foveal cone specialization and pit morphology in albinism

PURPOSE

Albinism is associated with disrupted foveal development, though intersubject variability is becoming appreciated. We sought to quantify this variability, and examine the relationship between foveal cone specialization and pit morphology in patients with a clinical diagnosis of albinism.

METHODS

We recruited 32 subjects with a clinical diagnosis of albinism. DNA was obtained from 25 subjects, and known albinism genes were analyzed for mutations. Relative inner and outer segment (IS and OS) lengthening (fovea-to-perifovea ratio) was determined from manually segmented spectral domain-optical coherence tomography (SD-OCT) B-scans. Foveal pit morphology was quantified for eight subjects from macular SD-OCT volumes. Ten subjects underwent imaging with adaptive optics scanning light ophthalmoscopy (AOSLO), and cone density was measured.

RESULTS

We found mutations in 22 of 25 subjects, including five novel mutations. All subjects lacked complete excavation of inner retinal layers at the fovea, though four subjects had foveal pits with normal diameter and/or volume. Peak cone density and OS lengthening were variable and overlapped with that observed in normal controls. A fifth hyper-reflective band was observed in the outer retina on SD-OCT in the majority of the subjects with albinism.

CONCLUSIONS

Foveal cone specialization and pit morphology vary greatly in albinism. Normal cone packing was observed in the absence of a foveal pit, suggesting a pit is not required for packing to occur. The degree to which retinal anatomy correlates with genotype or visual function remains unclear, and future examination of larger patient groups will provide important insight on this issue.