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

The molecular landscape of oculocutaneous albinism in India and its therapeutic implications

Oculocutaneous albinism is an inherited disorder of melanin biosynthesis, characterized by absent or reduced pigmentation of the skin, hair, and eyes. Molecular alterations of genes that cause non-syndromic albinism in Asian Indians are poorly characterized. This information would be useful for developing therapies for this disorder. We analyzed 164 persons with non-syndromic albinism, belonging to unrelated families from all parts of India, for molecular changes in the causative genes. Subjects with white hair, white skin, and red iris had their tyrosinase gene sequenced and were also tested by MLPA for deletions/duplications. Subjects with negative results or with darker skin, golden/brown or darker hair had sequencing of TYR, P, TYRP1, SLC45A2 and GPR143 genes. Pathogenic variants in TYR (OCA1) were observed in 139 (84.7%) patients, in the P gene (OCA2) in 20 (12.2%), in TYRP1 (OCA3) in two (1.2%), in SLC45A2 (OCA 4) in one (0.61%), and in GPR143 (X-linked ocular albinism) in two (1.2%) patients. Of 278 alleles with variants in TYR, 179 (64.3%) alleles had (p.R278*) alteration, suggesting the possibility of therapy with a stop codon readthrough molecule. We report 20 patients with 13 disease associated variants in the P gene and 18 novel pathogenic variants in TYR, P, TYRP1, SLC45A2 and GPR143 genes. The data are compared with those reported from India, Pakistan and rest of the world. The therapeutic options in albinism are briefly described, opening this field for future therapies.

Prevalence and predictive risk factors of self-stigmatization in patients with rare diseases: Based on health ecology model

BACKGROUND AND AIMS

Given the cause of self-stigmatization of patients with rare diseases is complicated, and the self-stigmatization can be prevented by managing the related risk factors. This study aimed to report the prevalence as well as influencing factors associated with self-stigmatization in patients with rare diseases.

METHODS

From January to April 2022, the respondent-driven sampling (RDS) method was used to select patients with rare diseases through the Chinese Organization for Rare Disorders as the subjects. Based on the theoretical model of health ecology, logistic regression analysis was used to explore the association between self-stigmatization level and sample characteristics of patients with rare diseases.

RESULTS

A total of 530 patients were included, 50.2% of whom were male, and most of them are under 45 years old (86.5%). The prevalence of self-stigmatization in patients with rare diseases was 85.7%. Logistic regression analysis indicated that age (OR: 0.624, 95% CI: [0.399, 0.976]), mental health status (OR: 0.184, 95% CI: [0.076, 0.445]), family relations (OR: 0.180, 95% CI: [0.074, 0.434]), full time work (OR: 2.835, 95% CI: [1.024, 7.849]) and medical insurance (OR: 0.296, 95% CI: [0.105, 0.835]) were risk factors for self-stigmatization of patients with rare diseases.

CONCLUSIONS

Chinese patients with rare diseases have a high level of self-stigmatization, and the potential risk factors are multi-level and multi-dimensional.

Ophthalmologic Phenotype-Genotype Correlations in Patients With Oculocutaneous Albinism Followed in a Reference Center

Purpose

Albinism is a group of genetic disorders that includes several conditions related to a defect in melanin production. There is a broad phenotypic and genotypic variability between the different forms. The aim of this study was to assess the ophthalmologic characteristics according to patients' genotypes in a cohort followed in the Reference Center for oculocutaneous albinism (OCA) of Bordeaux University Hospital, France.

Methods

A retrospective observational study was conducted in a cohort of patients with OCA seen in consultation in the ophthalmology department between 2017 and 2021 in whom a genetic analysis was performed.

Results

In total, 127 patients with OCA were included in this study and matched with the results of the genetic analysis. In the population aged over 6 years, there was no statistical difference in binocular visual acuity between the OCA1, OCA2, and OCA4 forms (P = 0.27). There was difference in ametropia between the three forms (P = 0.003). A two-by-two comparison using the Bonferroni correction showed a significant difference in ametropia between the OCA2 and OCA4 forms (P = 0.007) and between the OCA1 and OCA2 forms (P = 0.0075). Regardless of the form, most patients (75.4%) had grade 4 foveal hypoplasia. There was no association between the grade of foveal hypoplasia and the gene involved (P = 0.87).

Conclusions

We described a genotype-phenotype correlation for the three most represented forms of albinism in our cohort. This study allowed assessing the degree of visual deficiency in young children with OCA.

Human Skin Pigmentation: From a Biological Feature to a Social Determinant

Skin pigmentation is the most variable human characteristic that can be observed and has been used throughout history to classify humans into distinct groups. Many factors influence skin colour, but the melanin pigment is considered the most important because its type and quantity can determine variations in pigmentation shades. The evolution of skin pigmentation started around 1.6-2 million years ago. As a result of migratory phenomena to places with less ultraviolet radiation (UVR) and other seasonal regimes, the selection of depigmented skin and different tanning capabilities occurred over time. Thus, genetic adaptation to new environmental conditions gradually led to changes in skin pigmentation. Despite the biological importance of pigmentation, variation in skin colour has led to social and health inequalities. Since Linnaeus, skin colour classifications have been used to describe different human groups, encouraging the misuse of a biological characteristic. This review examines the characterisation of pigmentation and its evolution through history and society. The unequal perception of pigmentation diversity has led to an incomplete state of dermatological training and issues in medical approach in dermatology. The consciousness of all these aspects increases the need to address and overcome dermatologic and social health disparities related to skin pigmentation.

Identifying the genetic causes of developmental disorders and intellectual disability in Africa: a systematic literature review

Objective: Genetic variants cause a significant portion of developmental disorders and intellectual disabilities (DD/ID), but clinical and genetic heterogeneity makes identification challenging. Compounding the issue is a lack of ethnic diversity in studies into the genetic aetiology of DD/ID, with a dearth of data from Africa. This systematic review aimed to comprehensively describe the current knowledge from the African continent on this topic. Method: Applicable literature published up until July 2021 was retrieved from PubMed, Scopus and Web of Science databases, following PRISMA guidelines, focusing on original research reports on DD/ID where African patients were the focus of the study. The quality of the dataset was assessed using appraisal tools from the Joanna Briggs Institute, whereafter metadata was extracted for analysis. Results: A total of 3,803 publications were extracted and screened. After duplicate removal, title, abstract and full paper screening, 287 publications were deemed appropriate for inclusion. Of the papers analysed, a large disparity was seen between work emanating from North Africa compared to sub-Saharan Africa, with North Africa dominating the publications. Representation of African scientists on publications was poorly balanced, with most research being led by international researchers. There are very few systematic cohort studies, particularly using newer technologies, such as chromosomal microarray and next-generation sequencing. Most of the reports on new technology data were generated outside Africa. Conclusion: This review highlights how the molecular epidemiology of DD/ID in Africa is hampered by significant knowledge gaps. Efforts are needed to produce systematically obtained high quality data that can be used to inform appropriate strategies to implement genomic medicine for DD/ID on the African continent, and to successfully bridge healthcare inequalities.